I've spent most of the last two or so years working solo (engineering wise) professionally. I'd say the biggest con is that it's lonely. I've gone weeks without talking to people at work. I think that would drive most people crazy :).

I'd say responsibility is the same for me as I've only worked at small companies as a generalist. But yeah I suspect if you come from big tech land, being the everything person might be super tough to get used to.