Gran Turismo 7 does something similar, placing cones on the side of the track for major braking events, turn in points, apexes and corner exits. It's cool and non intrusive.
GT7 does have all sorts of tracks though, including road circuits on the countryside. F1 races exclusively on FIA Grade 1 tracks.
Genuine question, at this point don't you think it's preferable to look for in-track reference markers for your braking points? There's pretty much always a distance board on the side, so if you're going to work on an assist that places virtual markers outside as well I think its usefulness is debatable.
The racing line assist is mischievous, pal. It makes you think you're learning the circuit when in actuality you're learning to take the assist cues (colors) on your peripheral vision.
The shift to no racing line is more often than not one of method, so to speak. You consciously look for references outside, just like at first you're consciously looking for the racing line turning red when learning the track, just to then rely on unconsciously registering those as you shift your focus to actually driving and looking ahead.
I still use the racing line if it's a new track (or one I've not been to in a while) and I know I don't have the time or the will to put 2-3h learning it. Heck, I thoroughly love F1's racing line when I just want to plug and play! Love it to bits, don't take me as no assist hater or "git gud you tin can" kind of fool 😂
But it's not really teaching you the track. Turn it off on hour favorite, most raced on track and you'll most likely struggle to hit those apexes 🙃