I think sexual intimacy can be okay at an earlier stage, as long as you ensure clear and honest communication beforehand about expectations and comfort zones.

Completely fair point. It's definitely a lot more nuanced than I wrote.

In my eyes, I find that there's a lot of pressure to have sex, and very little pressure to hold off. This is especially true for inexperienced people. People will tend to rationalize themselves into having sex, even when in hindsight they really weren't ready. So to avoid having to consider edge cases and/or irrational thinking, I find that just setting a hard-and-fast rule where you just really should not have sex for x amount of time ends up being the simplest and most applicable advice