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That’s because they are massively overplayed compared to impact on the team winning a game.

Outside of Mahomes in 22 (17.2%) and 23 (16.9%)
The next highest paid QBs as a percentage of CAP were
Steve Young at 13.1% in 1994 and Brady at 12.6% in 2001

Paying a WR 30m …approx 10% of the CAP is nuts
You need more than 1 WR….and even then they touch the ball maybe 8-15 times a game max….and the worse the teams QB the less impactful those touches are likely to be:

The difference between the 30th best WR and the top 10 is fairly small at least compared to the difference between the 30th QB and the top 10