Final Cut Pro in it's early iterations ( Pre FCP X) was a kind of
linear-non-linear editor ( the paradigm being drop clips into a timeline of tracks, then change and adjust) that rapidly became 2nd only to Avid that already had a huge industry user base. FCP X completely changed FCP's editing paradigm in 2011 which is the point where many of those early users, not just indies, TV companies, broadcasters but the whole range, simply hated the change and fled in droves.
Take a look at this, I was pleased to see it still up on the net - it sums up editors feelings and how they were slowly won back by Apple
https://offthetracksmovie.com
What changed? I was editing and teaching using some of the early NLE systems, FCP, Avid, Media 100 etc at the time. In the X the system components, functions, controls, methods etc were all renamed and changed, many fundamentally. For example, the familiar FCP, Avid etc media management terms " reels, clips & bins" so named to follow the traditional film terms were replaced with a complex & very powerful metadata keyword system- everything had to be relearnt, muscle memory, shortcuts etc became useless, in fact it was a serious problem to overcome. The old FCP drop clips and slide around became a very much more complex & powerful paradigm with magnetic timelines and so on ... The list of such examples is very long.
Many hung onto the FCP final version, keeping older Macs and OS as long as they could. Finally most pros fled, this meant Apple had to find a new user base. FCP was I believe nearly abandoned at the time, it struggled. But eventually the Pros returned, the suite of Motion, Compressor and FCP and it's vast number of creative plugins became a powerful force in the industry.
Now you can integrate FCP ( the X was ofc dropped) with frame.io a cloud based system where edits, cuts and the editing process itself can be shared with teams with a net connection, with IOS,Mac OS, anywhere. Share rough cuts with the client, anywhere, anytime. Mark them up, make notes, change them- whatever. Integrated chat ....
Now it's fast becoming the industry leader in some sectors again. The younger user marketing is merely a tack on these days.