it is a nice theory but the problem with this theory is that if they want to mine, they would go legit and use GPUs or even mining equipment, meaning they would invest in it to really mine and share in the reward (even very small amounts) with their investors.
but scams do not want to spend anything, which means they would use the cheapest plan, only a domain and a hosting plan to put the website up. there is no more to that in order to mine even with GPU they would at least need a VPS or something like that which will cost which will lead to less money earned through their scam.