This is a by-product of the success of Ubuntu. Whether people like it or not, most software available for Linux will target Ubuntu first. There may be packages available later for other distros / systems, but on the whole, you can be sure a software developer will target Ubuntu if they target Linux.

It's hard to fight against a tide of "experts" and preset assumptions. Sometimes it does take tearing things down a little bit.

The formidable library of extensions is also a big draw: any browser based on Chromium can access all the third-party add-ons that help you customize your browsing according to your needs. If a development team wants to roll out an extension, it makes sense to prioritize Chrome. That’s where all the users are, and by basing your browser on Chrome, you get to ride along.