And the salary too. He will never find a club in this moment to even match his salary (unless it's Newcastle but Sterling will never go there).
Salah at Liverpool is battling to get his wages up and he is at least a regular producer and so important to his club. Sterling will always be the guy next to the main guy. I know he's a great player but I look at him and he's always just almost there. But maybe it's wrong to compare him with Tier A+ players as he is more to be compared to B+.
it is very difficult for him to move because he is hindered by an exorbitant salary and what you say is true, except with clubs of the caliber of wealth like Newcastle and PSG this reminds me of Bale, which is indeed a similar case.
and for sterling it's true he is a good player and a young player too but indeed the competition in the city is also quite tough so he doesn't get enough playing time.