The article you shared doesn't say anything about why blocks can take more than 10 minutes to be mined.
Quoting from the article
The network difficulty, already constantly increasing, has further increased significantly, making the creation of new blocks more expensive and complex.
BTW, it meant more advance infrastructure is required now to mine Bitcoin.
That doesn't explain why bitcoin blocks may take more than 10 minutes to be mined.
The article truly says that it's now more difficult to mine bitcoin than it was years ago, but that has nothing to do with why blocks may take more than 10 minutes to be mined.
First of all note that the increase in difficulty is due to the increase in the total hash power and with increase in the total hash power, the average block time should decrease (not increase).
Second, we have difficulty adjustment every 2016 blocks to maintain the average block time of 10 minutes.
It's possible that a block is mined in less than a few minutes and it's also possible that a blocks takes more than an hour to be mined, but the average block time is always (approximately) 10 minutes.
Again, blocks being mined more difficult doesn't mean they take more than 10 minutes to be mined.