Yes, I created Mithril. I also co-authored Fusion.js[1], which - in contrast - is about as "big boy" as a framework gets (and mostly works w/ the React ecosystem, if you're curious). We use the latter at over 100 projects at Uber.
Mithril fits in a similar camp as Svelte, and it does offer APIs for HTTP requests and routing out of the box. I've worked on projects before where I literally only had Mithril as a sole dependency (and this was with supporting IE10).
Fusion.js solves a lot of complexity-at-scale problems but it does so at a trade-off of not being nearly as geared towards standards tracking as systems like Svelte and Mithril.
Mithril solves all those issues well except animations, where it's just OK.
Interestingly, even though the Mithril community seems to be a home to people who dislike JSX, Mithril supports it better than React does. You can copy and paste HTML into JSX with Mithril; all the attributes line up. Also Mithril doesn't try to improve elements like <select> and <textarea>; it's all standard.
In personal projects I use Mithril. For medium to large organizations I recommend React. That's because Mithril does everything better than React except for maintaining backward compatibility and attracting large numbers of job candidates.
Do you think mithril will solve these issues or is a good alternative?