Interesting. I guess it depends on your definition of "serious amount of data". Our entire accounting system is built on Google Sheets, including about ten thousand transactions in four currencies per financial year. The system summarises by country and cost centre, and has sheets that provide our current profit and loss, and nice things like all the fields in each of the tax forms we have to complete.
OK, we are a small organisation, but I'm happy to recommend Google Sheets to anyone but power users. If you are crunching a lot more data than this, then I certainly agree that using a browser-based spreadsheet is not optimal.
My experience with docs was closer to the parent's. Sheets was fun for having a quick platform to hack out a few things for internal use, but it struggled to remain snappy for our org of about 120 persons. For example we had to start strictly tracking all POs and requests for spending and at first the sheet operation we had was okay, but it suffered once the entire department got to using it.
The admin panel was also horribly slow and just was a pain to work with, especially once we became the target of a long running phishing attack and would have dozens of accounts locked out every day. It was easily a 30 minute process to restore access to cleaned accounts since the panel at the time (2012-2016) didn't have a way of mass management of users.
OK, we are a small organisation, but I'm happy to recommend Google Sheets to anyone but power users. If you are crunching a lot more data than this, then I certainly agree that using a browser-based spreadsheet is not optimal.