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 your conclusion is wrong. Blocks being mined more difficult doesn't mean they take more than 10 minutes to be mined.
Blocks can be found shortly one after another within several seconds, or fter less or more than 10 minutes - the average block time.
With higher network difficulty, Bitcoin miners have to invest more to get enough powerful mining hashrate to compete with other miners from other mining pools to find block. In a simple way, same block time in 2024 and in 2017 does not mean same hash rate used to mine one block. Cost invests for mining in 2024 is higher than cost in 2017 or many years ago with smaller hash rate on the network and lower difficulty.