Instead of pushing back against your opinion, I must confess what you said would work if there was a seamless way to move accounts and communities from one instance to another. Unfortunately that’s currently not the case.
It’s also worth noting that an instance itself can change philosophy. It seems .world is moving from generic Lemmy to pro-world bank/imf/NATO Lemmy. I’m not necessarily for or against any of that, but I signed up for a generic Lemmy, not an echo chamber.