For all those wondering, extra shrink ratio is real - it's not just a made up thing, no judgements should be passed, some things just shrink more than others and that's a fact of nature.
Don't do that. It's the worst. Someone did that to me once and it's incredibly hard to convince others that it wasn't YOU that pooped YOUR pants. Such a mean thing to do!
Yeah I guess heat-shrink would do the job most of the time. But for when you have connectors that are too big to fit the right heat-shrink over or want to splice more than 2 wires together and want a waterproof seal over them this could be useful.