Influencers face backlash when whatever they're doing starts to become unattainable for the masses. For traditional Influencers, this can be going on a luxury resort trip funded by Tarte:
For running Influencers, it can be going to Boston, London and Germany on back-to-back-to back weekends and it being at least partially funded by Adidas. What some influencers (especially Michael Ko/Kofuzi, Matt Choi, and the entire Believe in the Run group) don't realize is that for a lot of their viewers just running one big city Marathon, maybe not even New York, Chicago, or Boston, is a once in a lifetime experience that people have to save up for. It becomes grating to watch the same people run race after race week after week, and afford it largely due to shoe companies comping travel (and bibs).
For somebody who has entered the London Marathon lottery 5 years in a row and not gotten in, it's pretty deflating to watch Kofuzi find a sponsor bib after posting a video ranting about how unfair the ballot process is when he didn't get selected. For somebody who ran 4 minutes under their age group qualifying time for Boston, it's pretty deflating to watch Matt Choi get an Adidas bib, start in the first wave and run a 3:30. Basically the problems you cite about elite runners being unrelatable also apply to elite influencers. What you watch is only possible if you have a huge online following. And getting a huge online following isn't really possible when other people have the market cornered and even if you put out high quality content for a long time, it might not get picked up by the mercurial algorithms.
We're already seeing the backlash to influencers in the running space, and not just on Let's Run. There are negative comments on many big influencers posts. Soon, deifluencers will rise in the running space and have channels dedicated to running a thousand miles, including your races, in a Brooks Ghost or Hoka Clifton.
And that's the natural cycle of Influencers. They eventually become too big and unrelatable, that spawns a backlash and deifluencers take their place. With running, a deifluencer (there's one micro deinfluencer I know who regularly runs 2,000 miles in a pair of shoes) will probably get injured and then that will spawn a new influencer who goes back to the shoe company standard of replacing running shoes every 300 miles.