The "iron is a solo mission" isn't exactly logical in comparison to what i'm suggesting. Currently ironmen have 0 benefits versus the many that the normal player does.
Regular Players can-
Create teams = Private chat & noted items when skilling in specific skills
Obtain hotspot = Killer XP bonus & an abnormally high chance of farming items that is otherwise not possible
Capture fort = More killer XP & tons of farming and skilling benefits
Automated events = Chances to win money and items donated by ironmen, normal players, and mods based on luck and complete RNG
It's not like I'm asking to be given free stuff and be able to to gain the ridiculous benefits that normal players already have. I created an ironman because I really don't have that much time to play except a few hours before/after work every day. So far it's been delightful and I honestly don't see why/how it would be game-breaking to allow ironmen to create teams with only other ironmen. I see ironmen players constantly asking in global about specific ironmen information that normal players can't even answer because they've never created an ironman account/know how to do something solo. Being part of an ironman only team could cut a lot of global spam and actually help players in progressing their accounts and not giving up.
TL:DR
Normal players have a shit ton of benefits, what is a negative to giving ironmen the ability to create a team with only other ironmen? Saying "it's a solo mission" isn't really an answer as the only benefit we get from being a part of a team (after training the teams skills high enough to even get benefits) is noted items from skilling.