That's a tough comparison due to other factors. I was very active here in the 00's, much less so since. I can definitely say the boards were much busier 15 years ago.
HOWEVER, many niche message boards like this have lost traffic over the last 10 years to other Social Media options. Some message boards I once frequented are gone now. So the fact that this one is still going fairly strong is testament to what the Dis has built.
Over time though, if the "Legacy" and "Undesirable" fans really are weeded out, it will mean less traffic for sites like this. There will still be trip planning of course, but it will be transitory because most of those seeking advice will be less frequent visitors who don't discuss Disney just for the fun of it. And of course if they somehow morph into bigger fans who visit more often, they will then become "Legacy" and "Undesirable".
It's really a strange situation if you try to figure out the endgame in all of this. They say the Legacy fans don't spend as much per day or per visit, but what about over the course of a year? Who is buying all that merch when it is released? Who actually becomes paid
D23 members who are paying for the right to buy exclusive merchandise? Heck, if the Legacy fans are weeded out, and Disney really became a place mostly visited by occasional vacationers, D23 would be dead.
Think of it this way. Where would the comic book industry be if they decided they wanted to shed their loyal crowd to pursue less frequent fans who might be willing to pay more for a fancier comic book once in awhile.
If Disney continues to double down on this strategy, it's going to be very interesting to see if it is sustainable over the long term. Legacy fans may not spend as much on a given day or in a given week, but over the course of a year? Their lifetimes?