Again, I'm a TT fan, contributor even, and I will continue to use it in personal projects but probably never again at work. The issue isn't that TT is too powerful exactly. The issue is the power makes templates harder to understand and maintain for others and encourages bad behavior in devs, exactly as you say–

Sure you can [run DB perl code in your template.]

I'm not quite a View purist and it sounds like you personally do things Right®. Something like Text::Xslate almost necessarily leads to simpler templates. It's also much more strict, which leads to better practices and easier maintenance. Just to say it again, TT2 really is 1,000x slower than Xslate in some use cases and there are one or two other template engines that are also in the class of zippiness. I know template speed is the last on the optimization checklist but if the difference is 500 renders per second instead of 5, and you're in front of nginx or something which is capable of handling much more, it matters.

I don't discourage TT use out of ignorance but out of thorough familiarity.