It is. But you're not developing a lasting institution which survives any one individual's bus. Further, a team kept artificially small tends to produce crap due to understaffing. Large companies can also fund work on particularly interesting problems with a long-term pay off, something that many small companies don't do because they need profits now.
There are also substantial personnel issues with smaller companies: lack of HR, legal, finance. Nepotism, lack of accountability, etc all tend to be factors in smaller companies. Of course, benefits tend to be less too. (I've seen all of the above).
I would work for the right startup. But most don't meaningfully compete on the "adult" factor until they are distinctly larger than a small team.
I've never been yanked by big companies as a worker[1]; the smaller the company, the more yanking I've had to deal with. I attribute this to a present and functional Legal and HR team, along with money to hire adequately competent people.