Sounds good in theory, but there will be compatibility issues with Movecraft. Such plugins can (and will) be creatively abused in PvP or siege situations, such as clicking on an inaccessible stair to "sit" on it - and thereby teleport to it.

Can this not be disabled in combat?

there is a sit plugin that just lets u do /sit and will immediately sit you on the block you are sitting? I see no harm being that way so that you don't just sit and teleport to that stair block

the same plugin also has a /crawl function that lets you crawl by using a client side invisible block that forces a player to be in swimming animation

and infact I think having the ability to crawl makes leg cutters useless because if you are lay down low you can hit through the slab

It can be disabled in combat, but adding crawl for ganks sounds fun

what are ganks?

sit can only be emulated via a mount and dismount mechanic is abusable

I mean, crawling make leg cutters useless is absolutely a good thing. But there are many other ways they can be used in a negative manner.

Would disabling the usage of the command in combat tag fix any of those?