Not really hard to understand. I have multiple browsers (and I have more than I listed, about another 10, I think - I lose track sometimes
)
I prefer to think or my use as using specific browsers for specific purposes (probably because of the menus, extension support, just works for that purpose in my experience.
For example, I have one https site that just won't work with Safari, just barely works with Chrome or Firefox, but works great with Opera - so I use Opera for that - and it has bookmarks/tabs set up to make that a quick experience. I have a couple of other browsers that I use similarly, for specific purposes.
I call it using the right tool for the job. I only keep Safari and Firefox in the dock, the others are in a desktop folder