There are 2 reasons why we called the feature "Social Recovery" instead of "Shamir's Secret Sharing".
Both reasons you mentioned are proof that people should not use and trust any form of Shamir's Secret Sharing.
Lack is clear standards and confusion between different implementations are big disadvantages, and this was never widely accepted by bitcoin community.
Sure it can be better in some cases than holding simple paper with seed words, but this could be mitigated with one or more passphrases.
Adding extra complexity with obscure incompatible system is no go for me, and until I see compatibility with other wallets I don't think it's safe enough to use Airgap wallet social feature.
Lack of clear standards was indeed a problem. But the new SSKR standard is here to solve that. While it's currently not widely used, there are multiple implementations available in case one project shuts down. And adoption will probably improve over time (it's a very new standard).
The use cases for passphrases and Shamir's are very different. But even if you could somehow "replicate" some kind of social recovery feature by using passphrases, that wouldn't be a standard either, and you then have to make sure you remember how to recover it.
And you have to differentiate between
not being able to recover your seed in case a project ceases to exist, and having to put some effort into recovering your seed. Our code is open source, so you will always be able to recover it, it's just not as easy as downloading a different app.
But as I said, we do want to build on standards, and now that there is one (SSKR), we'll add support for it in the near future.