Well, if you fly 150 flights and maybe 180k BIS miles, you quite frankly don't need to do MRs.
On the other hand, I haven't made any long-haul trips this year, and generally not travelled as much as I should, and I count 22 segments and 21k EQMs (with probably 17k Bum In Seat miles) to my name, meaning I need another 8 segments to just renew my status.
I need to travel once more by the end of the year. Skyteam doesn't have a direct flight on the route I need to take, so that means I would get zero useful miles for my flights.
Or I could make a connection and get 4 segments and a few drinks at the lounges in the process!
At the end of this, I would be still 4 segments short. So I'll have to do another trip - effectively a little MR- to retain my status.
I will fly more next year, hence I want the status for the extra miles bonus, and because I really value the lounge access.
Now, I was only 8 segments short of the desired status to begin with.
Other people have higher targets to hit!
Unless somebody wants the last few miles to get an elusive award, or there is a "uniquely" cheap mistake fare, MRs are done for status and not miles.