Over the years I've seen plenty of pitchers throwing in the mid-70's in D3. They might have hit 80 something once or twice throwing in a Showcase. But in games they are cruising in the 70's. They aren't pitching, generally, for a powerhouse D3 that regularly attends the NCAA Regionals, but in lower level D3's? Yes.
The key, as with anything in life really, is getting opportunities and then taking advantage of those opportunities when you get them. A recruit throwing in the 70's is going to get less opportunities. Even a lower level D3 coach is not going to highly prioritize a pitcher throwing 75. But if you can get in front of them, show them you can locate, spin and move the ball and consistently get hitters out, it can and does happen.