Sure, also for example by said moving its own versions out of the wayYou can quite easily tell Steam to use your system libraries instead of its own.
But the thing is that a Steam snap package would not even experience the issue, its own versions being really private. The security angle I don't necessarily buy; it's very important that a vulnerability in a library and on a code path used by e.g. SSH is quickly fixed but that same library being in use by LibreOffice doesn't mean LibreOffice is now also vulnerable; and certainly not that the risk-profile is equal.
Yes, there's all the reasons for why you want shared libraries to in fact be shared -- memory use, central bugfixing -- but an entire system always keeping itself synchronized in such a manner means massive pain for external software suppliers; in fact too massive for there to currently be a significant number.
I think the overall software situation will improve by there being more, and this requires this type of decentralisation...