Question: Is ACT a 'DPS Meter'?
Yes and no.
ACT somewhat predates the popularization of the term in games such as WoW, so it's hard to say yes. If you assume a DPS Meter's primary role is as a small widget that calculates your DPS, I would have to say no. ACT's developmental goal was never to spit out easy to get DPS numbers. It was meant as a raid analysis tool. Encounter to encounter player comparison is merely a side effect of obtaining that goal.
Player culture has demanded that it fill that role, but I always intend for ACT to be a tool which allows you to analyze and better understand the game it is connected to.
I actually scoff at the term 'DPS Meter' in its most immediate meaning and get somewhat annoyed when ACT is referred to as one. If that's what you use it for, that's fine, but it's not the intended purpose even if features that follow that role have been added for completeness.