The 'guide' was meant to be tongue-in-cheek and was just a stealth Bungie troll/complaint. It advocated betraying your teammate if he got rockets first, because in the end you would net more points than you lost. What does THAT have to do with assists?
I'm confident that people just don't like the new assists system because it is different from the old, and people hate pretty much any change, of any kind.
Imagine if the current assist system is the one we've ALWAYS had, for a moment. Then, after several Halo games, it was CHANGED so that they were given out much more frequently. Basically, imagine the situation is reverse.
People would be complaining that assists are WAY too easy to get. That players just run around putting a couple shots into everyone, in order to rack up assists. That it's insane that someone gets an assist when they didn't even do 50% damage. "Why should someone else earn an assist, when I did more than 60% of the damage AND got the kill?" etc etc etc.
And again, I'd like to emphasize that IN NO WAY does the new system harm your rating. Because everyone you are playing with is under the same rules.