What exactly is the point in raiding when you have m+ ?! Unless of course you're precisely interested in the raiding experience.
If you play a class that can tank or heal, you can just spam m+ as either role, and get geared much faster and easier than by wiping in a raid for 4 hrs and not getting anything.
If your main spec is dps, and you're not interested in cutting edge content, but just some pvp on the side, then raiding is literally a waste of time for you. Just get a weapon for your tank/healer offspec, and jump into m+. Later on, you can even keep a 2nd set of gear in your inventory, to switch to.
In 4 hrs you can chain 5-6 m+ because you get groups almost instantly as tank/ healer, and no one cares about your rio score either.