[mortenjorck]

It's a prestige thing. The current wave can probably be traced to Microsoft in the early 2010s, with its bespoke Segoe type family. Google followed with Roboto, then Apple with SF, and now you've got everyone from Coca-Cola to CNN commissioning their own type families.

[janc_]

(Large) companies & publishers have had their own typefaces designed since long (centuries) before that.

It got cheaper since the same electronic font can be used for (almost) all sizes, design purposes, etc. though, so it's also happening more often now.