I mean static linking is not on by default either so you have to flip a flag as well. Adding -ffunction-sections -fdata-sections to the compiler and --gc-sections to the linker is not hugely difficult, although of course you have to make sure that the static libraries were built that way as well.

That being said I agree that even with that you'd still end up with a massive binary because of all the code that's actually used in one way or an other and all of the code that the compiler and linker can't statically mark as dead. In particular anything being called indirectly through a function pointer is almost certainly going to end up in the final binary regardless of whether it's used or not.

And even if a lot of the code gets removed it's a bit silly not to reuse the shared code in RAM instead of allocating pages containing the same thing over and over again. It's wasteful and cache-unfriendly.