I wouldn't say its a scam, but just like not your keys, not your bitcoins, it's similar, if you don't have the hardware with you physically, it's ... tricky.
I joined a few a long time ago, and they turned out fine. Later on, I had the opportunity to buy miners, and send it to some warehouse located in northern Canada (somewhere cold) and some guy from this forum will take care of everything. I think he had a few hundred miner hardware and an actual warehouse. I don't know if he still operates the mining farm today (most likely, I can easily check) but if I had to buy any ASICs today, I would most likely send it over to him to take care of.
The mined coins go to your address, so you have to take a small portion of that and pay him his hosting fees, which include network and hydro (electricity) costs / expenses. He has the physical hardware anyways.
I think what Blockstream is doing and some other large mining farms, they are "professionalizing" and "institutionalizing" the mining now. Also it scales well since they operate everything, large warehouse, large location, cooling, maybe a mining pool, etc etc.
You could live in a small apartment and not worry about running miners at home even if you had the capital. Just let someone else do it.
I think the idea is closer to something like REITS or REIT ETFs.