This section is much more of a history lesson and a noteworthy mention.
By definition, Pathogen is a runtimepath manager and not a plugin manager. However, in practice, runtimepath manipulation translates into plugin management really well. After Vim 8.0, there's no need to manipulate runtimepath to install plugins. However, if you have to use Vim prior to 8.0 (and you don't want to use full-blown package managers), Pathogen might make your life noticeably easier.
Pathogen was one of the earlier takes on plugin management and has heavily influenced the landscape of its successors. Many Vim users still use it today, but the influx of new adopters has stopped.
Pathogen is available from GitHub at: https://github.com/tpope/vim-pathogen ...