WHY NOT IN BRAZIL?

I don't think they've ever stated an official reason why they do it, they just exclude countries from those promotions seemingly at random even tho the keys themselves are usually unrestricted and can be activated from said countries.
Also, it's not just Brazil, I'm from Argentina and I've had to use a VPN to get those free keys every single time.

Bulgaria also seem to get excluded all the time in those :)

You may have misunderstood that not only Brazil but also all the regions listed are unclaimable.
CN,HK,TW,AR,BD,BR,BG,IN,KZ,KP,KR,MK,MA,MM,NG,PK,PE,RU,TH,TN,TR,UY,VN

I have no idea but shouldn't this be a question for Fanatical?
Also why the "Add-on/Tool" forum category?

I assume the answer to your why question is that because Brazil has the most cheaters (multiaccounters, bot farms) etc. they prefer not to include this country in their promotion because they spend a lot of money and have no positive effect from it.

But maybe they have a other reason, on top, as my assumed one.

Best question them -but i don't believe they will tell straight that they exclude a country because there are too many black sheeps-.

We can only assume and that doesn't help you in the end.

These keys are not free for them. They probably want to reward the site's biggest consumers and we are just out.

I think the most plausible answer to my question is Masafor's because Brazil is really the land of rascals, and everyone knows that