This is right, I had new roms for my previous device, Oneplus One, for years. My Perseus is in mint condition but it's going to have to be replaced because it's unable to keep up with OS updates.I'd blame Xiaomi, it's a shame that an expensive flagship is abandoned immediately after launch. It basically got a single update after one year and that's it.
"But we launch a new phone every week and don't have resources for update the old ones". They copy Apple in everything, but they can't copy the easiest one: Launch. One. Single. Phone. Every. Year