I agree it does depend on fans' definitions, but surely 'effective attacking football' is effectively whatever gets you lots of good goal-scoring chances, irrespective of style, possession etc. That's why I deliberately deviated from the 'attractive' part. So whatever exact phrase / terminology you want to give it, a long-term high XG does by definition suggest football that regularly gets you in a position to have high-quality goal chances (or lots of lower quality ones), thereby giving a relatively high probability of scoring more goals, surely we agree on that?
I'm not saying for a second that xG is all fans should or do care about (most of them hate it I find, though that's usually because they don't really understand it) - I'm just saying that in response to your comment that "xG isn't really a marker of attractive football" (which I absolutely agree with), it is nevertheless a marker of football that regularly gets you in a position to have high-quality goal chances (or lots of lower quality ones), thereby giving a relatively high probability of scoring more goals, and that's not something that any fans should be completely uncaring about.
Also, I'm not sure I agree that "stats don't really work in football" - the xG league table at the end of each season is a reasonable proxy for the actual league table for most teams (obviously there will be some outliers, as with most stats). So again perhaps it's just terminology here, but over the course of a season, if you have the highest (positive) difference between xG and xGA, you will finish in the top 6, and if the have the highest (negative) difference between them, you will finish in the bottom 6. That's not a 'rule', it's just what hsitory shows has pretty much always happened, proving the relevance / significance of xG. Of course stats should never be used in isolation, they are one of a number of useful tools (including actualy results, and what we see with our eyes) to determine how well a team is playing.