It usually boils down to them wanting to be in a less "restrictive" environment - less existing "stuff" to support feels like more freedom to make and own decisions and Get Shit Done ™️ their way. They don't anticipate that there is often less freedom in many ways.

Chasing PMF and the almighty dollar, no on-rails, just-click-a-button infra. No platform team to rely on, etc. They can often get hung up on how much work it actually takes to... Do work. Still, for the right person, it's a great opportunity. They can bring good practices and apply them over time.