A 20-goal a season striker makes a massive difference to most teams. Really hard to find one though. Even in the Top 6, there is Chelsea who probably need a 20-goal a season man to add to their squad. Though Giroud and Morata definitely have the potential to get those sort of totals.
Outside the Top 6 I think there are only a handful of strikers who can remotely aim of 20 goals a season (Vardy, Mitrovic, Arnuatovic, Ings, Richarlison, potentially Benteke if he ever hits form again). I'd be amazed if more than 1 of players got to 20 league goals this season. Maybe 2 may get to get 20 goals over all comps.
It's much, much easier said than done to get a 20 goal a striker in. Makes a huge difference and it's why you'll see the likes of Danny Ings going for 20M despite not playing for 3 seasons. A 20 goal a season man is as rare as rocking horsesh*t but teams like RS, Spurs, Arsenal and Citeh have multiple players who can realistically hit that target. Shows the difference in quality between them and anyone outside of that Top 6 bubble.
Getting one in to supplement Richardson, Siggurdsson and Walcott would make a massive difference. Needs a huge slice of luck and/or a massive chunk of money to get those sort of players in though. It's why Lukaku should have been valued more highly. Getting 20 goals a season for a team outside the Top6 is a really difficult ask.