Neverwinter's gear progression just to keep up with every new story module is pretty unforgiving. I never have whatever's considered "the good stuff" at any given time and always just wear whatever gear Cryptic has decided to make accessible through a vendor most recently in order to help people get caught up. Combine that with my main being a cleric (never the most fun class to solo), and I have reason to want to go into every new module with my pet tank by my side (never mind the incentive of simply wanting to play with him). Whenever we get separated while playing new content - even if it's only briefly - I soon end up calling for help, because while I can just about stay alive I'm finding it very hard and tedious to kill anything on my own.
In addition, I have many bad memories of running into gear walls on my alts. I still remember being unable to finish the lair in the witches' area in Sharandar on my rogue a long time ago - there was this one group of six mobs or so next to a cauldron that I just couldn't kill, eventually forcing me to give up and come back another day. On my hunter ranger I remember idling next to the demon spawn spots for the Maze Engine daily, waiting for someone else to come by and start it, because on my own it was a fifty-fifty chance of me just dying instead of successfully fending off the demons. It wasn't that long ago either that I had to re-think my control wizard's build because she kept dying while trying to start the dailies in Icewind Dale.
Now admittedly I overcame those challenges eventually, but I realised that fear of the fights being too tough has certainly been holding me back when it comes to newer content. Not only have none of my alts completed any of the campaigns past Underdark, but my main also still has lots of them unfinished, from times when my pet tank's interest had waned and I was too afraid to go back and try tackling anything on my own. It was only this week that I pulled myself together and decided to visit Bryn Shander again for the first time in one and a half years to progress that Storm King's Thunder campaign that I had abandoned not even halfway through. And what do you know... it went OK. Things died reasonably quickly and I found myself thinking that probably even some of my alts would do alright versus these dailies nowadays. It's just like the saying goes: once bitten, twice shy.