Not talking from direct experience, but from contact with someone who has, I do believe that it's a tough call both ways.
Not an issue in the Dakar of course as when you're out you're out, but a good working example of the situation, but for a slightly differant reason was in this years Sardegna rally.
Sam was riding his 450 r for Honda Europe in a rally where most were on more agile enduro's. For a reason only known to the organisers he was numbered in the 80's.
Now a rider like Sam, or any with aspirations and ability to win, is going to go for it, whether in contention or not (having picked up penalty but continuing) it 's simply part of their competitive make up and DNA.
Sam said trying to be competitive with 80 or so slower riders in front of him on a track like Sardegna was dam near suicidal and he was close to disaster on several occasions and did not escape unscathed! - but is he expected not to compete, because of the dangers of slower riders?
To say dust is not dangerous also, we only have to consider the Kemal accident last month. Sam was visibly shaken, both from the incident, but also what he went through in Sardegna!
Ok, not an easy situation, but unless you are going to run the Dakar principle, which you can't as it would kill the sport then it seems to make good sense to me?
You may or not agree, but I thought it good to quote a live example (if not exact, but demonstrating the principles and dangers) for reseeding that demonstrates the benefits.
Of course it can work the other way - 18 months ago in Sam's first rally, his engines blew on day 3 - day 4 he started at the back, didn't really have to navigate, won the stage and was nearly half an hour quicker than Coma, Fretgne sated " he went passed me like he was riding motocross" funny at the time and it was in the big dunes with space and no real dust, but such advantages are far less than those that disadvantage.