But if the prospective employer saw the kinds of companies I worked for and heard their reviews, they'd be silly not to try to hire me (especially in the current market). Some companies might think it is a red flag but I wouldn't want to work for such a silly companies anyway - These often don't do very well because they prioritise things like employee discipline over raw performance.

When you job hop a lot, you become very adaptable. I can start contributing high quality code after the first week. I can internalise the coding conventions and all the nuances of the code base straight away because I've seen it all and I understand the different team mindsets and dynamics really well.

If you job hop a lot you cannot build anything of substance or scale. Launching a first version of something in 6 months is great, scaling it globally and iterating 2 or 3 times is the part you are completely missing and cannot do in 6 months. This is why I think you need to spend at least a year somewhere to learn much of anything aside from writing code. Learning software design doesn't happen without hands on experience iterating on a major project.

Being adaptable and delivering a few one off features is junior engineering which senior engineers can coach through. Coding conventions differ from team to team, package to package adapting to these also doesn't mean you are a robust engineer. It means you are competent. Solid engineer are expected to adapt. All big software projects that stand the test of time have nuances and even possibly anti-patterns because the initial design missed something.

I'm not sure what you mean by "saw the kinds of companies I worked for" but if you worked at Google for 6 months, Facebook for 6 months and Amazon for 6 months it still wouldn't mean much to me. All it means is you are smart enough to get your foot in the door but not successful enough to succeed.

I disagree, most companies don't really 'grow' like you're suggesting. The odds of joining a company like AirBnB, DropBox, Facebook, etc... While in its early stages approaches 0% - There is a massive amount of luck involved. These kinds of learning opportunities are essentially impossible to come by. However, if you switch companies often and work for a range of companies at different stages of development, then there is a very good chance that you will have the opportunity to learn about all the different stages of development without putting all your bets on one horse.

99.9% of the time, the single-company mindset that you're suggesting just gets people stuck in a rut (I've seen it). If you've had a different experience then you're one of the lucky ones.