linuxmemes

They talked about apps being sandboxed and containerized

The idea is usually good. But not always; some application have to interact with others, requiring inordinate amount of tinkering to make them work: disabling some security features, giving access to way more mount points than required (usually doing so manually), etc. It's also an issue when a piece of software requires access to some capabilities that are not exactly standardized, although ymmv on that point.

Also note that some of the promised features are not inherent to snap, but to snap implementation on a vanilla ubuntu system. Meaning snap can exist on other systems, but won't do everything as advertised.

Also also, but that's more of a discussion topic, there is the point of defining the attack model you want to defend against. Sandboxing everything is interesting on paper. But the amount of hassle vs. the actual benefits, especially for individual computers, doubly so on non tech-savvy users that will likely just follow whatever tutorial is available online to make things work when they seem to break, is not great.

Relatively simpler solutions, like flatpak, mitigate some of the most annoying points to improve usability by end-users. AppImage goes a step further by just being the program and his dependency running raw. And then there's the native OS packaging system; this should be the simplest for end users, but there's usually no sandboxing (although it is possible to do), and requires more work from developers/maintainers. It's a matter of compromises. But snap is on the far end while being not very good and very annoying, which irks people.

Bad implementation, flatpak is much better or just normal packages