I've always viewed rowspan and colspan more as design & visual tools and tend to avoid them on data heavy tables.

Out of curiosity though, does anyone know if google is capable of reading and understanding the data within a table when these are used (eg: for things like showing in featured snippets)?

I know screen readers struggle with them and have always erred on the side of caution with anything data orientated but it would be handy to know. There's very little written about this on the web about it though...