Many companies see working at the same company for more than 2-3 years as a negative. Even if you love the company, you will be seen as stagnant and lazy.

That is a scary line of thinking IMO. If you work for 40 years and lived by that philosophy you'd have worked for nearly 20 companies. While if you're a freelancer that might seem normal, but as a normal salaried employee, that seems like quite a bit. I realize that "getting the gold watch" and hanging around a company for 40 years isn't the norm these days, but to be counted as a negative just because you stay at one company for merely 2 or 3 years seems harsh. Have you had experience with this sentiment? I haven't encountered it yet.