There is some truth to that, yes. But given that they're still around means that they're doing okay despite the questionable choices. Speaking from memory, they absolutely dominated the personal audio market (cassette players, then CD, then mp3/digital) - at least before the iPod came around. MiniDisc didn't stick around, but they still had players for every big format of the day. And let's not forget that they co-developed CD-DA.

They've made some strategic acquisitions (i.e. Minolta) and they're in the big three of pro photography. That's speaking just from my bubble as a hobbyist/semi-pro photographer - but now that I look at the Wikipedia page listing their acquisitions, there are literally hundreds of them.

What you're saying about phones specifically might be true, I can't speak from experience. When they had the P line of Symbian phones I still only had a feature phone with a monochrome screen - and by that time (which I remember reading in magazines) Nokia was the big smartphone player with a lot of Symbian phones sticking to the 320x240 format (so if apps were catering to that, there's the problem). I don't remember specifics about Sony Ericsson's flavour of Symbian, but it seemed weird indeed. As of the feature phones from that time, I remember that many of them supported Java and things were mostly the same across brands.

Generally what you're describing is almost as if Sony has wanted to be Apple - with the difference being that Apple has been significantly more successful in setting trends. Not a fan, but can't not admit how big they are.