First off, transaction fees, it shouldn’t cost me $30 to donate $10 to a tracker. Most altcoins, besides ETH, have sub $1 transaction fees ~~due to their lack of popularity~~. Second off, security. I don’t want my coinbase account (which is directly associated with my real life id) connected in any way to my private tracker account. You can buy from P2P traders, but it’s usually a pain in the ass and sold at a decent markup. Monero completely solves this issue due to its untraceability. I know most trackers are still hitting their monthly goals in spite of these crazy transaction fees and lack of full anonymity, but it would still be nice if they gave the option for less financially able or more privacy focused people to donate.