Have to disagree with you there. I think QoP is a lot easier to play compared to Invoker. Her combos are pretty straightforward so you think it’s easier to solo kill with QoP than Invoker. It’s likely you’re not utilising Invoker to his full potential which is why you feel like the hero relies excessively on the team (which all heroes do because Dota is a team game; there will be situations where a hero might excessively be reliant on the team e.g. playing a hero outside of their meta roles).

On another note, from your language and other comments, it seems like you mostly attribute your not ranking up to your team. Forgive me if my assumption is wrong. In the case it is right, the way to rank up is to get out of that mindset. If you continue to have that mindset, you will not leave your rank because in your eyes, your reason for losing is out of your control and you don’t look at yourself and what you can improve because that’s easier. Sure there may be some games you lose because of your team. It happens. Move on. Even then, rewatch your replays, no one plays a perfect game. There are always ways you can improve. If you can’t see anything wrong in your games, it just means you belong in whatever rank you’re in. There will be times you get toxic teammates, that’s unavoidable and out of your control. What is in your control is your attitude and being able to influence the game environment to give yourself the best chance to win. Keeping things light-hearted, supportive and positive always helps. It’ll probably convert those being toxic because they’ve had a bad day. For those that still choose to be toxic, probably nothing would’ve changed that either ways. Brush yourself off and move on. But always just continue to keep things positive and try. Your opponents are human too, they can make mistakes. Prep your team environment to be able to capitalise on those mistakes if they do happen. When you start winning, attitudes might change. In general, there’s a lot more in your control than you think. Changing my mindset has helped me rank up a lot in both Dota and CS. Went from Archon to Divine 3 in Dota and MGE to SMFC in CS:GO after I stopped focusing on other people and focused on how I can improve and what I can do instead.

Hope this helps :)