Well, the best real-world hint I can think of is diamonds - all those diamonds came out through volcanoes and there are a lot found in Africa...

From memory I think there's more mantle plum activity under Africa than any other continent, and the average elevation is much higher than any other continent. So even if activity is low recently there's reason to suspect it's been much more active in the recent past (thousands to millions of years).

A lot of time when I see stuff like this invoking meteor impacts I suspect it goes something like this - "Well, that grant is used up - no more trips to tropical paradise islands for more 'research' - but gotta get a paper published to justify using up all that grant money, so just say it was an asteroid since that doesn't require any field work".

Volcanoes may not work, but before invoking much rarer impacts someone needs to, for example, go to Hawaii and look under one of the old lava flows that went across a beach and into the ocean, and see if any of the sand melted into glass. If it didn't, then explain why it might be that it doesn't ever happen elsewhere either. Only then appeal to some other process that is orders of magnitude less common to explain the glass.

Impacts are almost a modern snake oil in science, except that they do happen and the really big (and rare) ones are major events (with very uncertain results). The lunar formation theories really need an impact but most other theories that invoke impacts (dinosaur K-T etc) seem not to worry about whether an impact is the likeliest answer or even particularly plausible.