I think containerization is going to be the future for applications in general. It would certainly make using different versions of Python easier.

Is containerization any better than static binaries for compiled apps (not talking about python/ruby/js apps here, but instead compiled ones like firefox)?

Many applications were never designed to be compiled entirely static, as much as I’d like that to be the case it isn’t possible.

Containerization satisfies the contract the application expects.

That is really the problem it fixes, dependency hell and dynamic linking.

That’s great on a personal level, but bigger picture, aren’t we going about this the wrong way?

If most people are using containers because “applications were never designed to be compiled entirely static”, developers should start designing their applications so they can be compiled entirely static.

It is an unfortunately hard problem that would take agreement by thousands to fix. Thus containers.

In pre-history this tool worked ok for some things, I don't believe it still functions on modern systems.

http://statifier.sourceforge.net/

Why? Using different Python versions is a solved problem and no containers are required for that.