Side-channel attacks are a thing, this is true. But they also cost a lot of time and money to develop. If you want something that can be applied to more than just a single target, that cost explodes. That is why the two most common places where side-channel attacks are developed are nation states and universities specializing in that research.
What is not helpful, beyond informing people of the existence of them, is to simply state that side-channel attacks exist and therefore nothing is secure. Even more so without demonstrating how they are real-word applicable and how that information should alter the direction of development.
Security is a nebulous word and is almost always used as an incomplete sentence. It lacks an important qualifier. Secure from whom.
Creating a side-channel attack almost always requires knowing a bit about your target. Doubly so for something as delicate as timing attacks. Also, don’t forget to take into account development time for said attacks. If the software changes at a rate faster than you can develop your exploit, well, that’s note worthy.
Making it more difficult for an application to extract information from outside the containment zone does in fact protect the user from practical attacks which do not require a nation state to develop. It also most certainly cannot protect you from everything. Such is the reality of existence. I’m not safe from a meteorite hitting me but my risk assessment shows everything is going fine and it is not worth the mental stress to worry about.
So in summation, I’m far more interested in focusing on our ability to get security fixes out to users in a timely fashion. Herd immunity can work for software too.