I personally have experienced two problems with experienced people in the early days:
1) The last company I worked at started out with an experienced founder/CEO and a few entry-level people (including me). The company was in the heavily-regulated and very conservative health benefits space, and we were attempting to do something pretty radical. Things were going great.
After raising the series A, they brought in a bunch of executives who had been very successful working at more traditional healthcare companies. Those people immediately started executing the playbook they already knew which meant our startup went from being agile and disruptive to basically being a smaller version of all the existing companies in the industry. It didn't go well.
2) After that, I co-founded my own company. We're bootstrapped so it took a while before we could hire people, but when we did start hiring, there was a big difference between the entry-level people vs. the more experienced people we hired. This is almost entirely my fault, but here's what happened: I knew the entry-level people would need guidance and mentorship, so I invested heavily in onboarding them, making sure they understand the mission, and so on. With the experienced people (who I already knew well) I trusted them to know what needed to be done and do it, so I didn't spend nearly as much time trying to align them with the goals of the company. Big shock: that didn't work out very well for some of those experienced hires.
Once again, this is my fault, not necessarily a problem with hiring experienced people in general, but it doesn't change the fact that our entry-level hires have all worked out great while the experienced hires were much more hit-or-miss.
I have no idea if that's what sama is talking about, but I definitely nodded my head a bit when I read his advice.