Yes, bootcamps teach you the basics of each part of the stack. I would make the argument that you aren't proficient in any of these areas, so to advertise yourself as such is misleading. I file my own taxes, but I don't refer to myself as an accountant.

I've yet to meet a bootcamp grad that can efficiently architect a relational database, for example. I know plenty of Sr. level front-end developers who wouldn't think to call themselves full-stack even though they know how to submit a user form that persists to the database. Same with back-end developers who know HTML, CSS, and pick your flavor of JS framework.

If you've worked in the industry, you know things change too fast to stay up to speed on everything. It's not impossible, but it's unlikely and unrealistic to have that expectation of someone once they are employed.