I don't know what the fuck are some here trying to prove.
Simple numbers from transfermakt - during his time here, Johnson has scored 26 goals and provided 18 assists. 44 goal contributions in total. That has came from 5935 minures on the pitch. That means one goal contribution for every 135 minutes. So a 1 goal contribution for every 3 45-minute halves played. That is pretty consistent return.
Though at the same time he does not progress the ball himself. Nor does he dribble past his players often enough. As the Doncaster game and mentioned 18 assists (more than many remember/perceive possibly) prove - he can also cross the ball, at least from right wing position. But very often it means that the teammates have to put him through with their effort and work. While for example Kudus can pick the ball in our half, run and dribble his way to the position where to put in a cross / cutback pass. Johnson is also much less likely to win the ball back from opposition and unfortunately more likely to lose the ball under pressure compared to Kudus (and also compared to Odobert).
So I think after making circles in one place, we reach back to same place - he does score and is quite a good finisher. But other areas of his game are limited. So in the end we can use him in specific games and roles. Today could be one of those - we should be able to control the tempo of the game also with Johnson on the field. And potentially to use him as secondary striker, combining with Richie in the middle. But that would have to mean Xavi on LW which is hardly ideal...