Many (not all though), of their best engineers and designers have left after the IPO, that's why. So, a lot of people that made it a success initially have move

Many (not all though), of their best engineers and designers have left after the IPO, that's why. So, a lot of people that made it a success initially have moved on. They don't pay super well, so the new people that came later on are not necessary the best. That's why Spotify has been slow on introducing new features or fixing existing ones.