The first is that the certifying authority gets paid by the candidates. Therefore the trend over time inevitably is to make the certification easier and easier to get so that the candidates keep paying them.
The second is that the field tends to move more rapidly than the certification. What does a certificate from 10 years ago about how well I know Python and JavaScript tell you about my current skills as a developer? Not a whole lot.
There are reasonable certifications out there put out by companies for those who wish to work on their technology stack. (Open source, not so much.) The company has the resources and motivation to make sure that people who are certified for their technologies are going to be reasonably competent. But now the certification becomes a sales pitch. The company shows you how to use the latest version of all of their tooling with all of the optional side products. You go out into a real company and they are a couple of versions behind and didn't license all of those optional add-ons. You, the certified expert, are likely to become the person asking for everything to be upgraded and for a ton of new licenses for stuff that is only marginally useful. This isn't necessarily in the company's interests.
True story. Many years ago I worked at a large FAANG. To limit how much time was wasted on bad candidates, they built a machine learning system to filter out bad resumes. In practice it was better than a recruiter at identifying promising resumes, but worse than a developer. But it limited how much recruiters had to bug developers with bad resumes.
The machine learning system picked up all of the things that you'd expect. For example someone who thought it important to list Microsoft Word as a skill probably isn't a viable candidate for a senior software engineer.
But the single strongest signal that it picked up was kind of interesting. At the time the MCSE (Microsoft Certified Solutions Expert) was one of the most popular certifications around. Anyone listing that was unlikely to be worth interviewing.
I don't think FANG companies are likely early adopters of that. They are all relatively conservative with hiring. Navigating the organization to find an internal champion who's incentives are aligned seems really tough. Internal established recruiting teams seem disincentivized to use a 3rd party certification. Using that might reduce the number/importance of the internal recruiting team.
Outside of that, the most important skill is gathering requirements, gathering requirements and gathering requirements. In the startup world this is called finding product market fit.
System architecture design and computational thinking are also necessary but I don't think any software engineer can do those well without gathering requirements which is basically about identifying product market fit within your corporation.
I'm fine with meaningless tests that don't prove anything, as long as I don't have to do them for every single interview. I would gladly study for a certification, because it means I get to do it once and then I can prove everything you want me to prove in order to get a job to change button positioning.