This seems to target the same group of people that have historically been way more leery of credit than their older peers. If you've mostly or solely been using a debit card for everything and don't have any other major loans from which to base a credit score (e.g. car purchases or mortgages), getting a card that we would consider "more" rewarding might be a bit of stretch. At least to start, anyway.

Even then, a lot of people outside of FT seem to prefer using one card for everything rather than spending the time optimizing their rewards. It's part of why Apple Card has gotten pretty good uptake, for instance.