Trust me, it's not a forum thing. Alen was known for his always-flat-out style, which during the heyday of ridiculously long rallies in the 70's and 80's wasn't that common approach. That made Markku so popular among the rally fans worldwide, but also cost him dearly; 1000 Lakes 1986 or RAC 1987 probably being the best examples of rallies where he should have just taken it easy instead of pushing like there's no tomorrow.
It's true that the moniker wasn't used as widely during his active years as it has been afterwards. In 2001, when Markku drove Rally Finland for one last time, the text on the back of his Focus WRC read "The original maximum attack".
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And another reason why he's still so popular (although this only concerns the Finnish speaking rally fans) must be the wonderful interviews he gave. It's hard to put in words, but there's something very unique and charismatic in his way of being dead serious, but still with a shade of humor.
I only saw him few times in action in the early 90's, yet he's my biggest hero in rallying.
edit. Has nothing to do with anything, but actually I've seen Markku's father quite many times. He used to attend the same ice hockey games I did with my father. Ofcourse I didn't recognize him at the time, but my dad did.