You look at today, we have McDavid/Kucherov/Draisaitl/MacKinnon who are all competing every year for the award.
This claim needs a fair amount of clarification as you are saying that over the past nine years, this foursome has a total of 36 Art Ross contending seasons between them; ones that could have taken a Ross away from Jagr if he played in this era.
2016/17 (
ONE AR contending season) - McDavid is the only Art Ross threat, Kucherov introduces himself to Mr. Ross while Draisaitl is part of McDavid's party
2017/18 - (
ONE AR contending season) - McDavid wins a fairly weak Art Ross, Kucherov argubly was there too before taking his foot off the gas at the end, MacKinnon introduces himself to Mr. Ross despite missing a few games, and Draisaitl regresses
2018/19 - (
TWO AR contending seasons) - Kucherov and McDavid are obvious, Draisaitl is again along for the ride with McDavid, and MacKinnon regresses
19/20 - (
TWO AR contending seasons) - Draisaitl and McDavid are obvious, Mac and Kuch are in the pack
20/21 - (
ONE AR contending season) - McDavid is obvious, Drai is along for the Canadian division ride, Mac is in the pack, Kuch is on the couch
21/22 - (
ONE AR contending season) - McDavid is obvious, Drai is in the pack, Mac is out of the Top 10, Kuch is on the couch for half the season
22/23 - (
ONE AR contending season) - McDavid is obvious, Drai is debatable, Mac and Kuch are in the pack
23/24 - (
THREE AR contending seasons) - Kucherov, MacKinnon and McDavid
24/25 - (
TWO AR contending seasons) - Kucherov, and MacKinnon, Drai and McDavid miss to many games
So a total of 13 AR contending seasons, of which, 7 are non-McDavid seasons.
Starting in 1994/95 to 02/03, there are 7 AR contending seasons (no Mario):
Lindros - 94/95
Selanne - 96/97
Selanne - 98/99
Sakic - 00/01
Iginla - 01/02
Forsberg - 02/03
Naslund - 02/03