I have to admit that I don't like the look of the linked page at all.
It might just be me but I see no indication of why a download manager is required at all (outside of wget) and I also notice that almost all the suigestions require installing packages outside of the repositories.
As mentioned above, I am not entirely dismissive of multiple-connection downloading and, as it happens, I've nothing against installing third-party software on Linux. However, that Debian doesn't have this type of "download manager" in the repositories makes me doubtful of their utility.
If Gentoo, Arch, Fedora and Slackware are similarly missing them I would suggest that the major Linux developers don't think they're worth bothering with.

first of all I totally agree with you. But actually I do not care about that, I just wanted to show the available software without thinking about their usability. OP will decide....
last but not least I think there can be a reason to use download manager, probably not for increasing download speed but because of auto retry and other features.

Fair enough, and I agree about things like auto retry. Funny though that they decided one should add a repository for uget when it's likely included in Ubuntu, Mint etc. as it is in Debian.