I don't really care what they do. You can't use their browser without signing up for an account, which is absolute hypocrisy and even WORSE than regular browsers.
Was there some other privacy-touting or "alternative" browser that came out in the last couple of years?
One thing I did find annoying after installing it just now is that it doesn't import bookmarks from Safari, but rather only Firefox. It would be nice if it did; in fact it would be cool if some browser would do bi-directional bookmark syncing with Safari, to piggyback on iCloud syncing across devices.
But the browser itself, the sync features etc., none of that needs an account. The sync service doesn't even have accounts, just a long string of words to serve as a the fingerprint for a sync chain.
In fact, I don't know of a desktop browser that requires account signin. Chrome encourages it, but you don't have too to be able to use the browser.