The crux of it is that it allows for commercial use without needing to distribute the source code. Whether that’s a good thing or not depends on who you ask. There’s basically a continuum for open source software with GPLv3 at one end and MIT at the other.

GPLv3 guarantees that corporations can’t play games with patents or weird DRM to hobble an open source library and tie it to their closed source product. A lot of corporations will specifically bar employees from using GPLv3 code out of fear it could force them to open source their proprietary code as well.

At the other extreme you’ve got MIT which basically says do what you want with it. Fork it, embed it in your projects, sell copies of it if you want. Anything goes as long as you include a copy of the MIT license along with your software.

Rust tends to get a lot of commercial usage so GPLv2 or MIT tend to be chosen over GPlv3, and between them most companies feel more comfortable with MIT.