My 1st is 26 now. We recorded 6 hours worth of Teletubbies and when she woke up at 5am, would put her in her car seat in front of the telly for 3 hours and go back to bed...
Too much telly, too long in car seat...you could go on.
But she read Chinese at Cambridge, teaches, is happy, in a relationship and well adjusted with a formidable curiosity for life.
Did the same with second, now 24, also curious about life, physics + Masters at Bristol, also happy and well adjusted.
By the time third DC came along, started to feel guilty, so much, much less TV.
She is anxious, low self esteem, utterly incurious about life... So, who knows? It's always going to be anecdotal unless you look at an absurd number of studies, controlling for just about everything.
This no telly thing under 3 is rubbish, IMO, so many variables, birth order, etc... Waning parental resources like tiredness, trying too hard to achieve perfection can be more damaging.
Try to be alert and sensible about rearing your children and just aspire to be "good enough". Listen, engage, reasonable boundaries... And be good to yourself!