In a broad interpretation, such a practice could be interpreted as innovation stifling. Buy a solid player and covertly shut it down -- (1) no expenses for you outside the buying and (2) others might/will be discouraged to progress in the area because you, Alphabet/Google sent the message that you will do things in the area.
On the contrary. Blizzard cancelled a project also called Titan which they had never actually publicly announced.
Also Microsoft's unreleased booklet PC, Microsoft Courier. Never officially announced as anything other than a concept, but they did offer an official notice that the project was canceled.