I accept your points but for me the 'mechanics' aren't so important... or whether boarding passes can be issued... but whether the bags can go all the way through.
Qantas refuses to through check bags on separate tickets on separate alliances... which is inconvenient for me. Qantas would rather lose my business on the MEL-SYD sector than through check bags to BKK on a combination of QF->TG.
Rather than recognising my plans might change... that I might have to add a flight here or there... that a single ticket might not always be possible... Qantas would rather lose my business for domestic, and sometimes international connections because they make it too inconvenient to have to collect bags.[/QUOTE
All airlines have bean counters who make certain decisions on aspects of the business that you may or nay not agree with.
They may view 'losing' your business as short term loss for long term gain or you may just be collateral damage.
If I have a long transit I always check with the gate agent to get them to manually confirm my bag has made the connection.
They tap away at their computer, or make a call, but I have no idea what they actually do, or whether it means anything. But it make me feel better
The gate agent may be calling ops who has access to the baggage loading info to see if your bag tag is showing as scanned ie loaded on to the a/c.