People keep saying that.The problem with a mmm deck is that they limit the use of the tractor for other uses, and aren’t fun to remove and install.
I disagree. People have different experiences.
I can take my deck off in 1 minute, and put it on in 2 minutes. I've had this discussion many times, so I even made a video of me doing it. It's like anything, practice helps, and so do some good tips. I can do it without lying on the ground, and I don't have to heave the deck around. It's actually quite well designed and somewhat self assembling if you use it how it's intended. I reckon it's as easy to put on and take off as a 3ph implement is.
I take my mower off when I use the loader for anything serious. I take the loader off when I mow. Loader takes about as much time to attach/detach as the mower deck does.
I'm not saying that everyone should have a MMM. Plenty of people like rear mowers or zero turns or whatever. I'm just saying that we shouldn't give people incorrect information. For some people MMMs are a great solution.
Kubota B2601 MMM deck removal and reattach