At some point, reading kernel code is easier than speculating. The answer is actually 3. there are multiple semantics for filesystems in the VFS layer of the kernel. For example, XFS is the most prominent user of the “async” semantics; all transactions in XFS are fundamentally asynchronous. By comparison, something like ext4 uses the “standard” semantics, where actions are synchronous. These correspond to filling out different parts of the VFS structs and registering different handlers for different actions; they might as well be two distinct APIs. It is generally suspected that all filesystem semantics are broken in different ways.
Also, “hobby” is the wrong word; the lieutenant doing the yelling is paid to work on Linux and Debian. There are financial aspects to the situation; it’s not solely politics or machismo, although those are both on display.
You tried to apply far too much pressure over too large a surface area. Either make a more focused approach by not chasing Free Software and XMPP supremacy at the same time, or find ambient ways to give people options without forcing them to make choices in the direction you want. In particular, complaining about bridges usually doesn’t get the discussion to a useful place; instead, try showing people on the other side of the bridge how wonderful your experience is.
Also, I get that you might not personally like IRC, but you need to understand its place in high-reliability distributed systems before trying to replace it; the majority of them use IRC instead of XMPP for their disaster recovery precisely because its protocol jankiness makes it easier to wield in certain disaster situations.