My intuition tells me that we overestimate a bit the contribution of flight search tools in the overall cost of living analysis of a destination.
Certainly, they give the price of a ticket, but they don't really inject new information about daily expenses once on site.
The pattern I see is that people focus on the initial cost of the flight and forget the rest.
For example, a cheap flight to Dublin will have no impact on the price of a pint or a hotel; these are independent costs.
This link would only be very strong if these platforms directly included budget estimates for living costs by city, which is not the case.