I think smartphones are big contributors to RSI
In a way, phones are a 'dumbing down' of the computer. The interface is much more simplistic (conceptually) and thus the capabilies are more limited. There is a 'bottleneck' compared to a more load-balanced approach to input devices like with a PC.
Any 'real work' is not going to be getting done on a phone, but the 'illusion of getting things done' certainly applies here; theres a whole routine involved when you own a smartphone: unlocking, checking, swiping, syncing, charging, etc. But how much meaninful work really gets done on thse things? How much of the physical and mental effort that we invest in them actually returns value? And how much of it is brute-force, mindless effort being mistaken for valuable effort? In other words, how efficient? How inefficient? What costs are being incurred on your forearms, elbows, and eyes, for example?
More broadly we can take text messages, for example. This issue precedes modern smartphones - texts are nothing new. Since the late 90s they have been dumbing down conversations. This 'post-it note' style of communication is clearly inferior to email when the conversation reaches a certain level. The problem is that too many people rely on texting for all or most of their communiaction, and that leads to over-use of mobile devices, and stunted communication that often mis-represents the intent behind the messages which compounds difficulties all around.
A few links that we can dig into further..
nisg.org.uk/the-mobile-technology-revolution-and-the-rise-of-rsi
synergyrehabinc.com/repetitive-strain-injuries/
flexispot.com/spine-care-center/the-hidden-egonomic-risk-of-mobile-devices
squirrelworks
Phones and RSI