The shorter attention span idea is an interesting perspective on this. I’d have thought fidget toys like electronic pets etc. might have the same effect of inducing attention diverting behaviours but as you said, my experience of Facebook/Snapchat at the time was mostly static images. There was video on Facebook and to be fair we watched a lot thanks to many Australian phone plans zero rating data for Facebook but we didn’t do that during class.
I still think of myself as a ‘digital native’, as in this technology has existed my whole life, but in many ways yeah I agree with your perspective that it was not as pervasive during my formative years and I guess that makes all the difference here.