Are they causing more problems than stuff before? Probably! Much of what's on it is explicitly designed to be addictive. But I suspect it's by a relatively minor amount, and mostly stolen from other also-bad-for-you options that have declined / been out-competed. People have done this kind of stuff for literally forever, phones didn't invent it.
1: Not to imply they should or should not have that stigma. Just that they exist and work as a distraction too, and few people will immediately judge you for using it, unlike many also-popular alternatives.
If we've got stuff to talk about, it mostly comes up other times. Down-time and idle-togetherness is good.
On the other hand, there's something you could try called meditation. Though I wouldn't do it for two hours as you may literally lose your mind.
Your brain can not signal its status to you like a limb, saying ‘this is too hard’ or ‘this hurts’. While this barrage of input at the end of the day may relax you in some ways, it is hard work for your brain.
The effects of a tired brain are varied, but include trouble sleeping, memory issues, trouble reasoning, but also and often emotional issues(!) like irritability or sadness. Consider this in the light of the relationship issues discussed in this thread.
Much has been made of mindfulness as some form of spirituality. It is also a way to give your brain a break in an economy that is set up to hold your attention for as long as possible. Like many here, I’m quite saddened by the inability or unwillingness of my loved ones to direct their attention away from social media.