Yep, Rascal. I too have made many weird changes from one airline to another, and its never been a problem. Even sometimes on multiple tickets they manage to join them up on check-in. Sometimes they can issue boarding passes too so you don’t need to use a transfer counter.
I think whether they interline or not has more to do with costs and liabilities rather than airport technology. Part of the interlining thing is that one airline can be left having to chase luggage that has gone astray via another. Also there are other complications - such as different luggage allowances and rules. Eg if I fly using my EVA gold card to HK in economy, I get 40Kg luggage allowance on the short trip. If, then, they interline with Oasis, will they check my entitlement with Oasis before letting me check-in with my 40Kg? Nah… they’ll check me through and Oasis will pick up the tab for the extra weight when the pilot loads the fuel. I think most airlines take the view its rough with the smooth, and its part of the overall service that people have “seamless” journeys when they change. LCCs like Oasis seem to focus on point-to-point journeys and keep it simple.
I know one chap who’s used Oasis from Taiwan to the UK (CI for TPE/HKG). He’s really impressed and it all went smoothly. Certainly I prefer Gatwick to Heathrow. He said the service was brilliant. He was in economy but travels extensively, in economy and business class - so I think he should know. He’s usually on China Airlines out of Taiwan.
For people who want to fly business class cheaply, Oasis often has some good deals. But the thing that still worries me is not having a through ticket - a missed flight can work out expensive if you need to buy a ticket to TPE at an airline counter at HKG. Think if I’m to do it, I would buy a flexible return from here to HKG and leave in good time. Should make the connection outbound no problem. If Oasis are late on the return, then it shouldn’t be a problem to step on to the next available flight to TPE.
EDIT: Re your point why would they have a transfer desk if PAX always have to retrieve their luggage anyway. Yep its strange, I’m not really sure. Some people travel hand luggage only - could be for them. Maybe to help with other enquiries… maybe for people that are late/can’t normally enter HK so they can be escorted to baggage reclaim??