To be fair to the committee, upgrading C++ compilers is already a chore, even with the changes as small as they are. Would you rather spend time updating your lambdas because they changed how capture works (a real breakage not long ago), or doing something of actual value? The only reason we finally updated from Python 2.7 to 3 was that the OS vendors dropped it, but it was effectively a waste of time. That aside, I…
I think it's the distinction between can and must. Right now you can preserve ABI across compiler versions if you want to (and that is indeed a desirable quality for some users). The pushback is against changes to the standard that would require an ABI break.