Tech is usually easy to pick up, and highly company specific. Any good engineer should be able to learn new tech, and things will change over time.
Culture is much harder to "teach". For me testing for culture fit has become much more important than tech acumen, particularly at more senior levels. You need to have a sense of at least whether the candidate aligns with the company culture, and is willing to fit.
Not doing this risks several scenarios:
a) The candidate takes a while, but finally fits with the culture. This is suboptimal but ultimately a good outcome.
b) Candidate refuses to fit with the culture. This will likely cause performance issues, and the employee will ultimately leave or get fired. Not a good outcome.
c) Candidate actively subverts the company culture. This is the most destructive outcome and can be quite damaging, particularly at higher levels.
Checking that someone will be a good fit for the company is better for both the company and the candidate.