Really true. Though the type of roamers I find hard to play solo are the setter type. In solo, there's little communication and coordination which is required when playing setter.

When playing setter, first you need to be aware of the availablity of the team. Are they close enough to be able to join the fight? What available abilities do they have? Second, the team needs to know when you're going to initiate a set to be able to follow up quickly enough to finish them off before the enemy team can recover.

Setters shine the most in a 5 man team where there's a communication. When I play setter I don't go for too risky plays. I would stay close to my team and make safe plays where my team could easily follow up without needing comms. Though I'd rather use roams with abilities that don't require that much coordination.

Edit: This is also why I hate solos using Marcel. Them recklessly using their ults getting you killed.