That's not entirely true. If you had a "gap in coverage" e.g. you were without insurance for too long (about 30 days?) then limits on pre-existing conditions, etc. might be an issue when you get insurance again. But if you were just changing jobs, going from one employer plan to another, it wasn't an issue (at least it wasn't for me, and I changed jobs many times before ACA, including going back and forth between employer and individual plans). And if for some reason there was going to be a gap between jobs, you could pay for gap coverage under COBRA, or get a short-term individual plan.