I'd expect those that require real time data, such as stock market bots or sentiment data providers, to scrape twitter (if they don't provide the data by other means, for example the "firehose", which is another great way to earn money).
None of this makes much sense.
Also, it's much more complicated than it seems. The web works because the data is public. You cannot think of it as "my data". (Especially not twitter, since it is really their users'!) Twitter is not higher quality data than any other web page.
If we accept that thinking, every home page would require a login to see that specific company's phone number of opening hours. Those pieces of data are also valuable, in the right circumstances! And then the web would either not exist or the account system required would be so wide spread that accounts would carry no value and the system would become useless.