M0 never had timers. The whole removing timers line is PR BS. (That has mostly served to cause confusion.) They are trying to claim that bumping M0 difficulty and rewards to M10 is the same as removing timers from low keys while conveniently forgetting M0 has a weekly lockout.
They are removing heroic dungeon difficulty and replacing it with current mythic 0 difficulty with increased rewards. For some reason they have convinced themselves that people who actively chose not to do mythic dungeons will suddenly become addicted to pushing keys if their difficulty of choice has been removed. I see this as a removal of casual content in an attempt to increase participation in mythic+ dungeons.
Where on earth did you read this? They explicitly said that few run Heroic/M0 because the difficulty is trivial and that they increased the difficulty of Heroic and M0 (neither going away) so that people WHO HATE TIMERS have relevant content to do beyond the first 2-3 weeks of the season.
“Those who hate timers” can run difficult content without a timer because M0 is a lot harder and stays relevant longer seems a far cry from “devs think those not doing M+ will get addicted to M+”… like what?!