Valuations are not always straightfoward, and we don't know Airtable's ARR. I see Airtable as an Excel + Repl SaaS replacement. Does that have a larger market available to it? Maybe! Also, it doesn't appear Airtable has any competitors in the space (whereas your example has multiple competitors; MuleSoft is at ~$300 million/year in revenue, Microsoft doesn't break out their Flow service revenue unfortunately).

I think Airtable and Zapier are both great products, and recommend both to clients, but they have different use cases.