So far, it just doesn't make sense to me how multiple sites and sources can have such differing ideas
If you do enough research across the web, of course you will find differing ideas. Some old school, some new, some from different manufacturers. I would actually be more surprised if you found everything to be in line in all that research.
I'm attempting to make an informed and logical decision about that, and looking for help that's more than simply "just do it this way".
TFP protocols are their own unique methods that have been developed and refined over many years by experienced pool owners perfecting what they call Trouble Free Pools. You are not going to find wildly different ideas across this site, it is just not that kind of forum. The site is not about debating different ways to manage a pool, or even really convincing others to follow the ways. It really is just about the thousands of pool owners who have found these methods to work best, and while of course you will find the information here to be consistent, the method just isn't for everyone. There are plenty of articles, references, and posts here to do all the research you need, but in the end, no one is going to tell you to "just do it this way". The site will try and teach, and others will help, but in the end, everyone has to do their own research and find what methods and what ranges work for them.
This guy managed large commercial pools for years before getting into the construction side of the business and I trust him.
Speaking of wildly different methods, a large commercial pool is just not the same as a regular residential pool and they are really maintained differently. If you trust his advice, then by all means, you should follow that. This site doesn't ever really get into managing commercial or public pools, the health recommendations, chemical levels, and bather loads are so much different, we like to focus on what is best for the average home pool.
Good luck in the research, I do hope you find the answers you are looking for. Like I said, this site and its protocols are unique, and in that thought, they do not normally mix well with other suggestions or protocols. If you want to jump into a TFP, then this is the site that will get you there, but if you mix and match protocols, it is rarely trouble free, and not a lot of discussion around the why or how the results will be. Many of new members have come here trying to follow the suggestions of a pool builder, or a pool store, and then try "some" of the TFP member suggestions, and doesn't usually work out so well. Pool Stores and Builders and Redit or Facebook have all their own kind of logic, and take stabs in the dark trying to fix issues or debate solutions, but with the TFP way, you are just that, trouble free.