I think you make a good point, however, I distinctly remember Sharpe passing the eyeball test as an amazing WR -- who seemed to be virtually unstoppable. I have a strong memory of Sharpe going off for 4 TDs against the Cowboys sometime in the Jimmy Johnson era and looking like Superman when he did it.
A quick look at his stats page and Sharpe was a 5 time pro-bowler an 3 time 1st-team All Pro during his 7 years career. Irvin was a 5 time bowler and a 1 time 1st-team All Pro. Yes, I realize Irvin didn't get as many targets.
My point in this is not to say Sharpe deserves to be ranked higher than Irvin in the 'All time great WRs' pecking order. Irvin is in the HoF and Sharpe will never be, however, I am indicating that back in the day when Irvin / Sharpe / Rice where all playing, most viewed the Sharpe / Irvin comparison as a toss-up.