From an ideological viewpoint, I agree fully. From a technical viewpoint, Excel is still the best by far. For a normal office worker, LibreOffice Calc is all they need out of a spreadsheet software. But those working in finance or in other power user roles will either not be able to switch or have a very hard time switching from Excel. Calc is a brilliant program, there is no denying that, but it is far from a drop in replacement for Excel