You can definitely merge in Google Spreadsheets, is this a ChromeOS-specific limitation you're referencing? There are, of course, plenty of other limitations of the Drive suite.
It's a limitation of Google Documents. You can try it yourself. Create a Google Document, insert a table (Insert > Table) and, er, that's it. If you want to merge table cells, you're out of luck. There's no function that will allow you.
chestnut-tree|12 years ago