My 5 year old struggled and needed a whole bunch of support.
my 8 year old was able to work on her own, but still didn't get anywhere near as good learning outcome as being in class.
Now, the reason why my kids didn't fail utterly, was because my wife wasn't working and could, just about support their learning. Until it sapped her will to live.
This is roughly analogous to junior employees. They need special attention, and providing that over remote is a challenge to scale. Not impossible, but a challenge.
You also need to factor in that Junior employees are more likely to have shit accommodation.
EDIT: I definitely should have mentioned that my children are learning from a laptop WITH very close guidance from my wife who is raising them full-time and with intense dedication!
lol Pretty big caveat
In other words, they are not at all just learning from a laptop.
My experience is that unsupervised education is worthless.