Comment by tialaramex

This gets you dynamic dispatch, roughly via the C++ route (inline vtables in implementing types). This means you must always pay for this on the types which provide it, even if you rarely use the feature, removing those vtables makes it unavailable everywhere.

A lot of programmers these days want static dispatch for its ergonomic value and Odin doesn't help you there. Odin thinks we should suck it up and write alligator_lay_egg_on(gator, egg, location) not gator.lay_egg_on(egg, location)

If we decide we'd prefer to type gator->lay_egg_on(egg, location) then Odin charges us for a vtable in our Alligator type, which we didn't need or want, and then we incur a stall every time we call that because we need to go via the vtable.