Parler was poor quality because it was a product of extreme political grift. People who work in politics unfortunately don't understand the mindset of actually high quality products or services. What they're interested in is quick and loud splashes to attract a huge amount of attention, pull in a bunch of capital/resources, and then underdeliver in the extreme in the hopes that the attention of the crowd will move on and ignore the failures.
This is of course a bipartisan trend, but as far as I can tell affects Republicans more.
It was absurdly poorly run--literally on Wordpress with very little security and obviously no bug bounty program. They probably have never even heard of the concept of a bug bounty.
All around disappointing. The next iteration, if it is to work at all, will require a complete mindset switch.