No backups. Unreliable uptime. And of course, no self-hosted option. If you invest yourself in your blog and take time out of your life to maintain it properly

No backups. Unreliable uptime. And of course, no self-hosted option. If you invest yourself in your blog and take time out of your life to maintain it properly then it's not unreasonable to expect control over your work. If Tumblr goes down for half a day then that means nobody can visit your site, and if you have something that needs to be posted as a matter of urgency then you're stuffed until it comes back up. Plus, what happens when Tumblr goes out of business?