To be honest, this advice is a little prescriptive and facile, and you self admit that it's pretty limited. Giving talks at a conference, working on crypto-consensus algos and research-oriented consulting -- none of that really puts you through the experience of owning something long term which customers use. That's not to say I'd disagree with it (certainly not a be all end all). The inclusion of nofap and relationship avoidance is a little prudish and odd, but I can understand the draw of intentionally ascetic focus. Nutrition is 100% an often underestimated thing when it comes to productivity -- calibrating your diet pays dividends when it comes to maintaining productivity. Finally, the note that pattern recognition is basic brain function and everyone has it is true, the exhortion to stop reading crap like politics and twitter is probably correct if you binge read it and don't consume it in a healthy manner, and who really does? What you're saying is that there are a lot of things that are inside your control. What's really here to disagree with?
If we read between the lines here, it's clear that the OP is struggling not with what they were literally describing (somehow not being smart enough) and instead something different (burnout and maybe depression). And, if that's the case, then, as another commentator noted, "mental issues can can make subjective impressions unreliable or misleading" -- if this is the case, planning for increased productivity and mental hygiene (as wonderful as that all is) is probably not going to be a very useful next step. The next step is addressing the root cause, which is career dissatisfaction, potentially early career dissatisfaction.
First of all, OP, do you enjoy the labor and lifecycle of permanently helping your customers solve their problems? It's okay if you don't particularly care about the customers you are serving now while on the job -- you can change that. It's okay if you're not the star producer for the team -- you're still early on in your career, and so you're still learning to how to produce like a professional. What's important is that you at least somehow like the act of problem solving for customers, and that you are orienting yourself correctly to ensure you remain growing. It sounds like you feel like you're not growing anymore, or that you're stuck.
Why aren't you growing anymore? Is it a feeling, or a measurable issue with a very specific metric boundaries where it wouldn't be an issue? Are you running into problems inside your company or team? Do you think it would still be there if you were on a different team, or one at a different company? Do you think your issues have to do with purely internal factors or a mixture of both? Anywhere in between here could be possible, but if you're early career, just know that having experience at multiple companies really reduces a lot of ambiguity into things. Don't back project your identity in stone based off of a single work experience. Companies are a lot more chaotic free-for-alls than they are well run meritocracies, so it's not always easy to accurately trace back your track directly to your capability. Of course, as you do gather more data, you will be able to detect patterns and trends, but they'll be specific to you as a person. I think that's why it's important to work with a professional or in other way focus on healing if you're at the point of feeling burnt out, which is necessarily something that you have to spend some dedicated time recovering from (having been there before, it has taken me months before). For some folks, it can even be years.
First of all, you need to find a new job. Even if the new one doesn't work out, you need to collect data and experiences about what it's like at different companies. There's a world of difference between a stagnating train-car, a sinking ocean liner, and rocket ship. Once you've been on more than one and can figure out what kind of a situation you're in based on pattern recognition, it gets easier. You'll learn to figure out what you like and what you don't like. I aslo agree with the poster who says speak with a professional. It will take effort to find a good one, but keep at it. It's really worth it. There are so many things I used to think were insurmountable, or which were things about myself that were fixed in stone which I could never change, and that just really wasn't true. It took patience, mental flexibility, persistence and a lot of individual failures to end up getting to progress and momentum. If I had let individual setbacks permanently stop me, it would have been impossible to have gotten to where I am now. Don't give up.