I got an email from Microsoft recently with that funny thin font used for headers. It reminded me that that was a trend around 2016 or so. The headers would have thinner font strokes than the body text, despite being substantially larger.

I remember that around that time (I was quite young) I was putting it in all my attempts at websites (all hideous, even at the time) and I thought it looked really cool. Funny the way trends go.

In the case of the email it was clear that it just hadn't been updated with the times.