bearodactylpeople often try to find the 'best' mentor they can in hopes that they will be spoon fed all the information they need to know to improve at the game
sandblastpeople ask me to mentor them. i give them a demo review then they usually never message me again
agree to both of these.
to add to bears comment, a lot of newcomer/am/IM/Main players refuse to do demo reviews with anyone who isn't top 2 advanced/invite. So a big issue is that all those players get filled up on all the demos they want to do, and most of the mid-advanced plus players arent actively looking. I've added newcomer-main players off of their tftv looking for mentor threads, and they say they only want an invite mentor. anyone mid advanced plus is going to be able to give you a laundry list of improvements, and those people probably have more time, which means more dedicated time to you as a mentee. the pool of available and eligible mentors is a lot bigger than most people think, you just have to be willing to ask the right people.
I don't think that some Main player who makes a post asking for someone to help mentor him will deny help coming from someone like me and or bear who have consistently placed 3rd in invite for well over 2 years+ now. The problem is not finding the right person to ask to mentor its the person being able to plan and mark dates when they wanna watch demos and consistently show up to demo reviews. Sorry but I'm not actively searching for someone to teach to play TF2 after people just ask me to teach them then just stop caring 5 days later.
I do agree however that most mid advanced players have the time to work with a invite player to get a ton better if they just ask. They need to ask the right person. I've even been offered money to do this for people for a whole season and respectfully declined due to past cases.