That is true. Some people do use those kinds of shorting services to borrow BTC and to short in that way, but I still say good luck if you believe that kind of system is going to work to cause bitcoin's price to crash at these prices and with the levels of capital that is likely to come into the space and the number of coins that would likely need to be borrowed in order to support such price declines, as compared with the likely number of coins to be bought as compared to sold.
I know some people are expecting that BTC prices are going to go down because of various kinds of shorting and these kinds of ambitions of BIG capital to drive BTC prices down; however, I doubt that ambition and the ability to borrow coins alone is going to accomplish the desired downward price movements.
I personally believe those kinds of downward BTC price betters are going to get R3ckt, and it is more likely that we are going to need a decent amount of BTC price going UP first, before the shorters are going to be able to have success in their ambitions... perhaps 1 year of accumulation and price appreciation at minimum, but perhaps could take 3 years or more before they are going to have sufficient tools in place.
yeah, I don't really believe some specific typical capitalist entity or group of actors aka "Wall Street" can short bitcoin down in the markets just because they feel like it or just because they can, just because they have deep pockets. Market rules still apply, and bitcoin is large enough now for it not to be quite that type of timid asset that would take kindly to newcomers trying to mess with it. Old hands have lots of coins and have been trading this for a while.
It's also not really fair though to say that futures wouldn't have an effect on spot btc, it will have some sort of effect, as many factors do, but they are all represented there in the graph and who's to say what exactly is the driving factor most of the time. 2nd guessing a million variables when all you really need is 2 is kind of a waste of time. It's generally a helpful thought experiment though IMO, to play with ideas about what people may be thinking and what new pressures may be in effect on the market. Personally my 2nd guessing is that crypto has grown very fast and wide this year and has a lot going for it in many ways, hype included, it's not going into bear market mode for a while yet, though I expect more of a correction/sideways action from here as there is a new context to this last big sell off and action that was more severe than any previous since the start of this big bull run, also seasonally more significant as well as straight out of a parabolic rise and a weak, low volume and fairly rounded top.