Blockchain should be singular - "blockchains" should be used when referring to the technology in general. Getting this wrong is the #1 indicator that an article on blockchains isn't worth reading.
I'm not sure if it should be plural when referring to the technology in general. "Powered by blockchains technology" doesn't seem correct to me.
I do hope you'll read the article regardless!
The word "blockchain" works just like the word "computer". You can have a blockchain or multiple blockchains, just as you can have a computer or multiple computers. And you'd refer to "blockchain technology" just as you'd refer to "computer technology."