The way you get funded is by being able to do things that others can't do, or by being better at some technique than everyone else. Giving away all your hard won tricks by putting all of them in a methods section takes away your advantage come funding time.
The problem is that it is far easier and cheaper to produce stuff that looks like science but isn't so if you fund stuff without being able to prove it/reproduce it then you will probably end up funding 90% bullshit while starving real science for money.
Any real scientists ought to recognize that secrecy as a strategy is terrible for science as a whole even if it is very temporarily good for them.
Though it should be noted that data sharing and dissemination plans are now required for many funding types, and I've been on at least two applications recently with very strict "You will share with others" requirements in them.
What's the point of funding something that won't help anyone because the author won't tell you how they did it? How is any conclusion that they've come to useful if nobody can verify if it's correct?
This can definitely be the problem. I've seen studies where 50% of funding came from university and 50% from a private company. University required study to be published in their database, company wants the end result and don't want media to know what they are working with. So the report is obfuscated just enough to be legible for publication without giving away too much data from the company.
Especially for final masters degree projects this is very common as the students don't get paid by the university at all, so many try to find a company to sponsor. But the students still need the uni to publish the report for them to get their final degree so you get this conflict of interest again. Most of these reports are just written with the end goal of getting a degree, not of creating solid research, this really needs the stricter universities not letting through all that crap, for now they shouldn't really be trusted the same way as proper research papers.
It is more subtle than you think. It is not that you give no information about how to do things, you lay out all the steps that you took in your methods section. An example of keeping all tricks to yourself is that you do not tell others about the 100 small thing you found out, the hard way, that you should avoid doing. i.e. You explicitly say in the methods section these are the steps I took, but what others really need to know is why you ended up doing all the tiny tiny things it the particular way that you did. In many cases, you could write pages and pages about all these reasons. All these little tricks add up to much greater efficiency. Good experimentalists are the ones that have already made all the mistakes.
Edit: This is additional context for the commenters below.
