[rcMgD2BwE72F]

What's wrong with download managers?

Should I only use the one provided by my Web browser? Should I not download the content that I want to access locally or share between devices without being obliged to stream/download it again from a server?

[vdfs]

There also some websites that throttle your download speed, you can fix that by using parallel download of same file.

[cptaj]

Some countries and ISPs do this as well. Lots of uses for download managers

[einpoklum]

The thing is, a browser is already "managing" downloads. If browsers implemented their internal download management reasonably, people would mostly not need to bother with an extension.