I mean, it's happened before, lol. Hannahowo was sucking dick and taking facials on OF the week after she turned 18, made about a half-dozen full-on sextapes later on, and yet she still hasn't shown her pussy after YEARS on OF.
It happens when girls are more self-conscious about how their pussies look than they are about having videos of them giving head out on the internet. Besides, CK has already deepthroated dildoes and stuck things up her ass on cam dozens of times, a simple real BJ video wouldn't be
that much of a jump (although I agree that these videos in particular probably don't have her going that far just yet).