The decision to disable the markers was made by two council members (if I recall correct) last year December, see also the PR where the change was made from that time:
If you do not agree with this change, please make a new topic. It is unrelated to this topic about performance (and stability).
If people want to cheat they can cheat. Observers using a console command to place markers in the game in real-time would leave evidence of cheating in everyone's replay file. Doing it through voice chat would be basically undetectable.
This is not the consequence of the exploit. I'm leaving it vague on purpose because I do not want to give it more attention than it has to have.