In the last 3 years, two biggest bicycle component manufacturers have released their 11-speed MTB groups, along with press releases, containing high quality picture and video content (aka "sick edits") creating the desire to own them. Just like in early 2000s, the true advantage of going "one more speed" was increasing gearing range. From Shimano side 9 speed hasn't really brought anything new to the table than smoother gearing ratios for those who (pretend to?) care. Some liked that shifting got smoother and less clunky but I myself still get pleasure-filled flashbacks of 9-speed Sram X0 shifter derailleur combo going Cling! Clang! Clong!, making me more than sure that the selected gear is on, VS Shimanos soft cleng-bfleee-click. 10 speed attracted many due to larger cog going from 34t to 36t which created a psychological illusion that NOW I can finaly crank it up on single chain ring. Unless you were riding a 29er, 2 more teeth didn't make much of an actual difference. Illusion or not, along with chain guide development, 10 speed drivetrains really made many people dare to go for single ring setups and that was great due to chain retention, less cables, less elements to fail or just maintain. Then clutch mechanisms in the rear mechs came and further decreased the chance of dropping the chain. I was still dropping it, but very very rarely.