Exactly, which is why we have so many other metrics nowadays that we can make a judgement on & average them out so we're comparing apples with apples as best we can.
Johansson faces more difficult shots, saves more shots, has a higher save % (awful stat by itself) etc. We can look at the Post Shot xG (chance that a shot on target should be scored) to assess how difficult saves are & then average it out. Johansson beats Wilson on every one & that's before we even look at the fact he successfully takes more crosses etc.
De Gea is an excellent shotstopper but his all round game is incredibly poor. He has the most Clean Sheets though so by your metric he's the best keeper?
On your last point, I think it's just that the game has changed so much. They need to be good at coming for crosses, good with their feet & probably the overall quality of finishing has improved too. Oggy wouldn't survive in today's game for example.
You are right to single out Lloris though. He is one of the most overrated keepers around for me & has been for years. Always has a clanger in him. Only Alisson & Ederson kept more Clean Sheets last season though so....
