Imagine someone wanted to open a new service for let’s say video hosting and is doing so for political reasons (e.g. the creators feel that YouTube is banning/“deboosting” anyone posting Islamic content). The operators would be well served to manually verify new accounts when starting that service to keep things such as anti-Islamic material, child sexual abuse material, other illegal content, etc. off the service until they have a scalable and automatic moderation solution which has been battle-tested. I think most people would agree that simply putting up a new service like that with no guardrails will go badly.
Therefore, please keep in mind that Parler was a new entry into the social media scene and lacked the opportunity to develop robust community content/sentiment controls over the course of a decade such as Facebook and twitter. The generally stated purpose of Parler was to provide a safe space for individuals who were banned from Twitter or Facebook for what Parler operators would consider political reasons. Parler certainly does not want (in the long term) individuals removed due to highly incivil or illegal behavior (from Parler’s perspective). Requiring a manual verification before the account begins algorithmic “boosting” is reasonable in this situation, at least to me, until Parler can develop better automatic/scaling moderation tools.