Of course stuff happens, but I would be very cautious about calling it a defect tensioner before all the other possible stuff has been looked at.
It may sound stupid, but you could first check:
1.) You have a decent quality oil filter? Beware, They do sell some really crappy stuff in some parts.
2.) Are you using the wrong oil viscosity? Too thick oil takes too long to properly get into circulation, That causes "no oil rattle" on startup, just as a drained oil filter.
3.) After you take the valve cover off, the chain should sit on the pulleys tightly with almost no play, Check by hand. That lets you evaluate the plunger-ratchet of the tensioner. Btw, they hardly ever go broke.
4.) With the valve cover off and while you are at it: Have you measured valve play? See the FSM about how to.
Nice pix, Fummins!