It's not necessary. Indeed there are many GCs that use type information (as a sibling comment says, Go GC is now precise). But it's more complicated, so it's a

It's not necessary. Indeed there are many GCs that use type information (as a sibling comment says, Go GC is now precise). But it's more complicated, so it's a tradeoff. You may pay some little cost in dealing with tagged arithmetic but you gain a simpler GC codebase, one perhaps that can work with both the AOT and bytecode compilers (just speculating)