When everyone started playing 4-3-3 or 4-5-1 about 15 years ago, probably Mourinho who started it, strikers evolved a bit into 'forwards' didn't they.
Most strikers now are wingers who can shoot. Same as most full backs being wingers who can run all day and defend a little bit.
To play in the three you've got to be fluid, quick, able to create and score, technically brilliant, really intelligent and interchangeable and press like maniacs. Wind the clock back 25-30 years and people like Sadio Mane and Ronaldo and Rashford would be playing on the wing in a 4-4-2.
You still get the odd proper number 9 like Lewandowski or Aguero or Kane but they have to be exceptionally good. Even someone like Lukaku, who is superb, looks like a bit of an anomaly in a world of Rashfords who can do it all.
Jordan was missing most of those qualities, just not very athletic, couldn't hold the ball up, didn't play in the air. I remember him being slightly better than a pure fox in the box poacher but not that much better, certainly not worth playing up front on his own.
Same way you won't see maverick wingers like Ginola who just stand still and do their hair when they don't have the ball anymore, you won't see proper poachers like Defoe or Rhodes or Inzaghi much anymore when 99% of teams either do hard pressing or fast counter attacks.