Success isn't binary in my opinion. While we obviously would've wanted to win more trophies under ENIC (I guess it's their fault we've not scored in our last 4 finals and bottled countless semi-finals?), it is ridiculous to suggest that any team can just spend money and win the league or CL at will.
Everton have spent £500m and are on the brink of relegation. There are so many clubs that in the same era as ENIC's tenure have achieved absolutely nothing too. Newcastle consider themselves a big club and have done fuck all. Villa, Sunderland, Leeds, Everton, Notts Forest, just to name a few. These are probably all clubs that considered themselves equal or bigger than us when ENIC took over.
Why do those who are anti-ENIC never credit them with raising the expectations to where they are today? The reason that we consider Europa League below us is because under ENIC we've enjoyed a CL final and multiple CL runs/top 3/4 PL finishes.
If you turned around and said "They've done a great job on the infrastructure of the club, they've given us a lot of good memories over the past 10 years but I don't think they're the people to take us to silverware" then I'd potentially agree with you but the rhetoric is always some nonsense that we've been massively unsuccessful because they don't spend the money and we always get compared to those in the upper echelons, not the many, many clubs who have failed below us.
I repeat, we are literally such an expectant fan base in 2022 because of what Levy and ENIC have built during their tenure. If we had had 20 years of mid-table and bottom half finishes, we would not be looking down on the Europa League.