massage and sex - is it all just about the 'happy ending'?

Never had a massage or really given one so I dunno why so many porn vids of people getting massages are just a means to get sex and 'happy endings'.

Always seems to be girl/girl mostly, then guy/girl. Never seen any guy/guy 'happy ending' vids - I reckon there would be too much 'wrong hole' action ewwww