Solutions can vary from game to game but in some cases, it’s not a matter of whether or not there is a true solution, it’s a matter of “Is the solution cost-effective?” Remember when Blizzard had great customer service? When you could talk to GMs and get real responses and solutions to your issues before this garbage ticket service that gives you robot replies? Paying a bunch of people to solve problems vs having a robot do it isn’t as cost effective.
There are companies that know they have a problem but either choose to ignore it or accept the level of failure occurring as acceptable within their capability. For all we know, Blizzard may have ran some studies and determined that they are ok with the level of cheaters there are.
Regardless, yes, playtime is not a good determining factor. It “sounds” simple but it’s been proven that there are several gamers who in fact, do play a ton. The statistics on that can be debated to death. An MMO I used to play tried doing playtime to combat botters. There was even a point where if you were doing a certain activity for more than 5 hours, you were banned for botting. There were people who would grind for 8 hours at a time and got hit with the hammer.