How do people actually fall into the "Tankie" mindset?

After seeing a megathread praising Mao Zedong, an actual mass killer, and a post about a guy saying "99% of westerners are 100000000000% sure they know what happened in 'Tiny Man Square' ... the reasons for this are complex and involve propaganda ...," I am genuinely curious what leads people to this belief system. Even if propaganda is involved when it comes to Tiananmen Square, it doesn't change the atrocities that were/are committed everywhere else in China.

I am all for letting people believe what they want but I am lost on why one would deliberately praise any authoritarian system this hard.

Can someone please help me understand why this is such a large and prominent community? How have these ideals garnered such a following outside of China?