Disclaimer: I do not personally run my youtube channel as a business; I am only giving general information from my studies as a tax accountant. I am not your tax accountant, though, so I would highly recommend consulting one regarding the particularities of your own situation.
Although a sole proprietor who has no employees technically doesn't need an EIN, you can always get one with the IRS anyway. So you don't need to form an LLC (even a single-member LLC) just to be eligible for an EIN.
Similarly, the deductibility of business expenses is not about the form of business that you have, but about showing that you have a trade or business rather than a hobby. So again, having an LLC vs sole proprietorship is not strictly necessary here.
And finally, starting separately accounts for business-related income/expenses doesn't require a separate business entity, either.
So, then, if you can do all the things you were thinking about in a sole proprietorship, why might you want to do an LLC instead?
Well, please note the "LL" in LLC stands for limited liability. As a sole proprietorship, your business is really the same as you. You're just taking money out of one pocket to the other. As a result, if you were to have any lawsuits or financial setbacks, your creditors could go after your non-business assets. (keep in mind though that even as a single-member LLC, you'll probably be asked if you try to get loans, etc., to put personal collateral on the line.)
If liability doesn't seem like a big risk to you, then it might be worth sticking with a sole proprietorship with a DBA -- that would probably be a bit cheaper and have less paperwork.
