This is true. I agree with the overall premise of the article, but claiming that Opus is more used than Sonnet is just wrong.

One of the graphs even lists a "Claude 3.5 Opus", which does not exist. After 3.5 Sonnet was released, 3 Opus largely fell into irrelevance until they decided to finally release another big, expensive model with Opus 4, which still isn't anywhere near as popular as Sonnet 4 with users who pay API prices.