I'm a bit mixed on this matter. It's yet again an example of how these institutions decide for you what you can do and what not, but on the other hand it will somewhat prevent mentally challenged people from harming themselves.

It's a given rule (at least for me) that you shouldn't spend money that you don't have. Putting yourself into debt just to buy yourself some Bitcoins or whatever or coins or assets is just retarded.

People however will have their ways to avoid this measure and still be able to invest with money that they don't have. It may require them to take an extra step, but they will successfully achieve their goal anyway.