I'm flabbergasted that we once again have this conversation with you, Barry. How many times do we need to prove a fact?
Sometimes two people can be correct in some matters, and this is one of them.
Why do I say we can both be correct on this? There is a difference between someone laying out facts, and the way users actually do things, based on interpretations of those facts.
For instance, Tim Berners-Lee, who invented the World Wide Web is glad it's become ubiquitous; however, he's very, very unhappy at how it's been so monetized and therefore restricted from how he would have liked it to be used by ordinary people. Does that negate Berners-Lee's original thinking? Of course not. Once in the "wild", the Web became something different.
Closer to home, when John and Thomas Knoll invented Photoshop - before it was bought by Adobe - it was all about photography. Quickly, however, the program became a kind of all-purpose tool, used to design web pages, for graphic design, font design, graphics for video, and on and on. Lightroom itself is the result of Adobe recognizing they had left a core customer - us - behind. Does that negate Photoshop's usefulness, or purpose? Of course not. Lightroom is a response to real-world need and practice.
So my suggestions here, based on real-world use and advice about posting images to the web are based on how the users of images, and the developers who answer the needs of those users, have suggested images be processed.
Does this make you wrong in your assessment of the science and physics of image use on the web? Of course not. Will ignoring my advice and only paying attention to your advice cause any disasters posting images on the web? Of course not. Will ignoring your advice and following my advice lead to problems posting on the web? No.
Here's another analogy: When the big camera companies sponsor famous photographers to promote their cameras, those companies' focus is actually not on the pros as their primary customers; their real customers are ordinary people, because there are many, many more of those than the pros. The pros are there as proof-of-concept to inspire ordinary users to buy their cameras because they have now been certified by professionals as good.
Here is where the role of a professional photographer and occasional web designer, such as myself, who makes a living doing that work, and who follows two industries' best practices for the use of photos on the web, comes in, as far as giving advice.
In addition, I used to teach a college class in professional practices for photographers, and now do workshops. Digital workflow is an integral component to surviving as a professional photographer, and like any teacher, it is incumbent on myself to be a good learner; that's one of the main reasons I'm on this forum - and on many others, besides, and why I spend so much time reading about and listening to how professionals do their jobs
In the end, both your opinions and mine are just that, opinions. Are they both based in fact? Yes.