The policy to fast-delete any post that falls into one of the off-topic reasons has existed for several years now and was based on a suggestion from one of the Community Managers. I believe the context was improving the quality of the homepage to users who are not logged in or who have low reputation, around the time of refining our scope, perhaps even around the time of the name change from Programmers to Software Engineering.
Since I fast-deleted it, the question before edits was about finding a programming language that matched certain criteria. Since it was essentially a resource request, it was up for closure and already had two close votes on the question. Since resource requests are one of the off-topic reasons that are difficult to salvage, it was fast-deleted as per the policy mentioned above.
It's also not true that there is no recourse for the community to contest the decision. Anyone can flag the post for moderator review or post about it on Meta. Most mods (and I believe all of the mods here) have a policy to not handle flags on things they are participating in unless there's something very, very wrong, so that's a good way to get another review on it. Posting here on Meta lets everyone with 10k+ rep chime in as well.
- Fast deletion of off-topic posts is a standing policy, but one that can be further discussed in general if people want to.
- It wasn't a unilateral decision to close since there were two other close votes already on the question. The deletion comes from the close reason.
- The post author and any involved user has opportunities to contest the decision via mod flags or Meta.