Yes in the fullest. For one thing it's against the ToS of every site. But it's also just plainly unethical. Even the most elite players are merely reaching a moderately accurate approximation of optimal play, which completely pales in comparison to a bot that can find it on every hand. Of course a bot that simply assumes opponents are playing co-optimal strategies will only be minimally exploitative, but more sophisticated bots can easily incorporate historical data and find correct maximally exploitative deviations against opponents in real time, which again is something that even the best players are only able to do accurately a fraction of the time.

Also it's laughable to suggest that playing optimally is "just the given" in MTTs, which are arguably the softest format available where almost nobody in a given field is playing anywhere close to optimal. And even more laughable to suggest that modern bots are akin to players adhering to SuperSystem, a poker strategy book written nearly 50 years ago which was already extremely outdated before the advent of solvers 10 years ago.