Earlier quoted context omitted.
Mind providing a source for this? I read this all the time but it doesn't match my experience here in Germany.
1.5 to 3 years doesn’t seem to be too far off the mark. https://insights.dice.com/2016/07/08/how-long-do-tech-pros-s...
Personally, I'd be disinclined to interview a candidate with >= 3 jobs on the resumé, none of which lasted longer than 2 years. Taking into account the time spent for them to get up to speed, and the time their successors would have to spend taking over their code, it seems unlikely that their tenure would make much of a positive impact.
Furthermore, a key driver of experience in software engineers is maintaining their own code over multiple product cycles. Job hoppers not only don't acquire that experience, but may actively fall into a habit of bailing as soon as they get sick of their own code.