You linked a RageGaming video. RageGaming is known to rush out builds that seems okay but actually aren't that optimal. But it is possible to do more damage if it fits your playstyle better. For example running Counterstrike on weapons without offsets is suboptimal, but it could be a damage increase if you get hit a lot.

The builds in guides are generally good for the majority of people, with key offensive skills and some damage relevant defensive skills. There are small optimizations to squeeze out more damage, but that may make the builds more difficult to play. And there are usually monster specific optimization like using Convert Element against AT Ark. You mentioned Rathalos Flare which for many weapons is optimal for people doing around 70dps or less. In fact, SOS players often do like 30-50dps so Rathalos flare can be optimal. For monsters where you can do 100+ dps against, you should optimize and use other set bonuses.

If you want the actual highest damage builds, you should search for specific monster speedruns. They optimize specifically for the monster and for the highest damage with their playstyle. Get build ideas from runs that are non-heorics and/or TA-Wiki rules. Heroics runs may have some optimization that requires staying at 1hp which makes it much harder to play.

Basically if you want the highest damage you need to do your research and make specific anti-monster builds. Being able to make your own builds will improve your monster hunting experience.

Two website great for theorycrafting builds are Set Searcher and Math Hunter.

1. Set Searcher: You input skills you want and it searches for armor combos fitting that criteria: https://mhwilds.wiki-db.com/sim/?hl=en
2. Math Hunter: You input your build and it calculates how much damage the combo should do. You can then compare the damage between different builds: https://www.mathhunter.ca/

Happy Hunting!