There are philosophical and technical reasons to not like snaps
Technical
- Slow startup time
- Makes lsblk look really ugly
- For awhile users didn't have a lot of control over when things updated
- Not designed to work with third party repos by default
- Requires apparmor so it doesn't work well on selinux distros.
Philosophical
- Backend is proprietary and controller by a single company
- Has made the same amount of effort as flatpak to work on distros that aren't Ubuntu
- Some people just don't like Ubuntu