I doubt it's a hard on.
Do you know how many times in the 2nd half of the season (the half when Rabiot played non-stop) we had at least 4 available midfielders including Rabiot? I actually checked this:
from 21 January to 23 February, on April 1st and 2nd, and from 11-14 May.
That's a total of 39 days when we had more than 3 available midfielders.
5 days in February, 31 days in March, 28 days in April, and 19 days in May (total of 83 days) we had only 3 or 2 available midfielders. Rabiot didn't get a single injury in the 2nd half of the season, hence why he played non stop.