This is a counter argument to having a constitution that allows the president to do what Macron did. There are basically nothing stopping him besides tradition and good will.
Every multiparty system allows someone to do what Macron did, it's baked in. When no party has a majority, multiple coalitions are possible. Someone has to choose which of those possibilities gets the first opportunity to make a government.
As far as I know, by tradition, Macron should have taken the NFP's candidate as prime minister even though they only had a small majority. Then the assembly could have censored the government or not, basically triggering a new election if they did.
Macron, knowing what we want better than everyone else, took a shortcut by making shoddy alliances with the traditional right and the far right to name Barnier.
The only reason he refused to name Castet was because she wanted to reverse his retirement reform (which was also rejected by the far right, so it could have actually been removed). But the official communications were all about "nobody really won the election" or "it would be ungovernable".
Macron is a child throwing tantrums because what he wants is best and he knows better than us peasants, he sees himself as a benevolent dictator, as in, he is making the tough decisions because he knows he's right. And in our constitution, the president has extensive powers that allow him to act in such a way if he wants to, with basically no checks and balances but honesty and tradition.
And in all that, some members of his former government won seats at the assembly, and kept their positions as ministers too. So we had deputies-ministers, wrapping up the "urgent matters" and setting themselves up for their next jobs. They effectively wrote budgets that, they themselves will vote for in the next few weeks. That's effectively breaking the separation of power
Technically the left didn't win the majority of seat in the parliament. They have a relative majority as in they are the biggest group in parliament by a small margin but they don't have the majority needed to make a stable government.
A majority vote from the parliament can oust the PM and his government.
If you take all the right wing parties, they hold the majority of seats (2/3rd). A left leaning government would last 48 hours, so in spite of french leftists telling everyone they "won", they didn't.
Our electoral system is very flawed though and the current make up of the parliament is not representative of what people want, there are much better voting system for plurality based political system that could be implemented.
That's my point. In a multiparty system, it's rare for a party to win a majority. So someone can win even though the majority prefers a different person.
For example, suppose there are three candidates A,B, and C. It's possible for 60% to prefer A over B, 60% to prefer B over C, and 60% to prefer C over A. No matter who wins, a majority agrees that they are worse than another candidate.
And if the leader of the second biggest party would rather work with the third biggest party?
Then the biggest party could well remain out of government, because someone decided that a different coalition would form the government.
The virtue of a two party popular vote is that once the votes are counted there is a clear winner determined by the voters, and nobody can change the winner behind the scenes.
As long as the coalition represents the majority, I don't see why the largest party needs to be part of the government. The largest party doesn't represent the will of the people by itself, otherwise they would have a majority.
Coalition building happens in a two party system, too. The difference is that it happens before the election, not after. That way the voters, not the coalition builders, get the final say.
Counter examples exist. Willy Brandt was social-democratic German chancellor in a coalition with the liberals while the conservatives were the biggest party in parliament. The conservatives could only watch.
Also recent state elections in Thuringia, the fascist AfD is the biggest party but nobody wants to work with them, so they don't get a chance to form a government.
What's important in both cases: the majority of voters want it that way. They wanted a social-democratic+liberal government under Willy Brandt and there is a clear majority in Thuringia that don't want the AfD to govern. In both cases it's more democratic to not let the biggest party govern.
The United Right alliance placed first for the third straight election and won a plurality of seats but fell short of a Sejm majority. The opposition, consisting of the Civic Coalition, Third Way, and The Left, achieved a combined total vote of 54%, managing to form a majority coalition government.
So exactly the opposite of what you said.
The party with the largest number or seat didn't get to make a government and the largest coalition who managed to get a majority of seats did.
They did get thay opportunity from the president. The prime minister didn't get a vote of confidence after a month of trying to pull a majority together. But they did get a chance, unlike french left.
France has a Head of State, the President, and a Head of Government, the Prime Minister. The PM is appointed by the President. The President is the head of the Executive branch, and the PM is the head of the Legislative branch.
From the Wiki:
The political system of France consists of an executive branch, a legislative branch, and a judicial branch. Executive power is exercised by the president of the republic and the Government. The Government consists of the prime minister and ministers. The prime minister is appointed by the president, and is responsible to Parliament. The government, including the prime minister, can be revoked by the National Assembly, the lower house of Parliament, through a motion of no-confidence; this ensures that the prime minister is practically always supported by a majority in the lower house (which, on most topics, has prominence over the upper house).