Trust me, you get plenty of experience in this as a founding engineer in a startup.
Many of these comments make me wonder how many people here have actually worked at an early stage startup in a lead role. You learn a lot about what's maintainable and scalable, what breaks and what doesn't, in the process rapidly iterating on a product to find your market.
(For readers, I don't think there's anything wrong with that but it just means that certain perspectives are overrepresented here that may not be more reflective of the broader industry.)
The idea that this is means "you don’t learn the actually valuable lessons" is completely baffling to me.
Most people I've know with founding engineer experience or similar leave not because it's not challenging, but because it's exhausting.
Increasingly I've realized that the HN community and I are not even speaking the same language.
Even in areas where startups aren't literally creating new product categories like the foundational model providers, the edge of a startup over a more established business is the speed at which they can provide value. What's the point of buying CoolCo when you can go with L&M Inc. that has thousands of headcount working on your feature. The value prop of CoolCo is that CoolCo can roll out a feature in the time it takes L&M to make a detailed specification and a quarterly planning doc breaking down the roadmap and the order of feature implementation.
Now be part of the team of folks that keeps that application running for 10, 20, 30 years. Now be part of the transition team to the new app with the old data. Those tasks will also teach you a lot about system stability, longevity, and portability... lessons that can only be learned with more time than a startup has.
The technical challenges are _very_ different between these environments. In a small company you have to deal with technical breakages all the time, but you don't really have systems-level problems.
Then customers and market changed so you also most likely have different customers.
I had to undo a lot of over-engineering to fix performance issues that was implemented in good faith by people who ultimately left the company and they thought they did a good job future proofing our product.
I am with company from start and now it is 11 years. I knew why they built it like it was so I was able confidently what to fix. But it still took almost a year to undo stuff that was making our current customers miserable.
Obviously very few, because these roles are impossible to get into. What else did you expect?