The “case” has little directly to do with the “why”, as the data statistical history is neutral and reflected warning patterns seen in the market in previous cycles, warning sings that do not care about why the markets became over valued.
The case is the valuations themselves compared to those valuations in the market history. The history suggests that when those valuations get above the historical averages or even worse above historic highs - regardless of why - they are signalling over valued conditions.
Your suggestion is to me similar to the excuses made for the dot.com bubble - “the economy is different”. Well, the fact that the market was overvalued did not care one twit that “the economy was different”, the market was still over valued.