Equating corporate background to a Company culture mismatch is quite a take tbh. You're a PHP-only shop, yet you see Too much emphasis on dated tech as a reason for rejection? ...an Application send by mail is considered "Applying on side channels"? You're a very small shop and seem very far from a corporate organization (something you yourself seem to despise, see above), so why should anybody care for your rigid application-process? I'd personally expect some resiliency from a team of 4!
I'm only writing this here because I feel that your rant really just feels like any unreflective rant, and you should really consider whether you'd want to put it out there as is.