I hate to break it to you, but the natural tendency is for people to seek out the maximum reward for the least amount of effort. 60% of the playerbase didn't choose the DPS role for the challenge. Most did it to avoid responsibility and fly under the radar. The remaining 40% took on most of the leftover responsibility either to secretly revel in the thought that they could kill off the party at any time ("If you get 6 more vuln stacks, I'm gonna do something about it... maybe.") (20%), or in a misguided attempt to use their encounter knowledge to hash seven single player games into something resembling a cohesive whole (20%). Even if you look within DPS jobs as a whole, people tend to migrate towards "pure DPS" over jobs that involve support interactions with their teammates, especially if they require coordination or communication.
Mechanics often specifically target DPS players because without mechanics, every fight is essentially a target dummy, and thus identical. Tanking and healing require you to understand the fight script, so no two fights will be the same, even in the absence of "targeted mechanics". There's actually a lot more thought required to design interesting tanking encounters, in part because raid positioning and movement is intrinsically more complex than being randomly picked to jump through a hoop every two minutes and coming back for a delicious treat. Even still, we go out of our way to dump these on tanks and healers to maximise uptime and reduce these fights to target dummy conditions wherever possible (What's a DPS jail?) DPS are intrinsically valuable by design. There are some incredibly talented players, to be sure, but the exception is not the rule.
To be honest, the only reason why there needs to be a dps discrepancy between pure DPS and "support roles" is because you'd otherwise just get your tank friends together and clear content. You'd just bring DPS along to cheer you on.