My basil plants are thriving too much.
This is my thai basil:
And in the same pot lemon basil:
I've topped them quite a lot, as you can see in the bushy growth pattern.
They already started flowering months ago, even before I put them into the big pot. I read online that you just have to snip them off, and done.
But there are basically only flowers coming, and I don't want them to waste all their power into developing seeds.
Is this normal and just a part of their lives when they reach a certain size?
It is normal and yeah once they start it can be hard to stop. You can try cutting them back more aggressively to see if that helps, but ultimately basil is a short lived plant and eventually it will flower and die.