Why is Ubuntu popular?

I am strongly wondering why is Ubuntu this popular. I don't feel like it addresses any "role" for a distro. All the other "big" distros are really specific into their specialization:

• CentOS & OpenSUSE : Server side distro
• RHEL & SUSE : Paid server side distro with professional service
• Fedora : Professional/Jobs Distro
• Debian : 100% Free Software Distro
• Mint : Starter Distro
• Arch : Customize
• Gentoo : Even more customize
• Slackware : OG Linux
• LFS : Even more OG Linux

Special Mention to ReactOS and FreeBSD which are popular distributions that aren't Linux but fill their respective need.

I am having a hard time why Ubuntu has become popular. I personally view it as a distro popularized by a private industry? Is it popular because it managed to build a community or because it's easy to work with?

Enlightened me please.