There are a couple of reasons why WHF isn't in top 5 any more.
Prices, because you need big units and a couple of characters, all that summed up means big cash, and that's something an adult gamer in modern times isn't willing to pay for toy soldiers. With other companies and even 40k you need of everything less which means you don't have to sell your kidney and you can even buy and drink some beers while you play the game.You can get the whole faction from other companies for the price of two units for WHF.
Size of the game, the number of models you need to play is ridiculous, you can't even use your kitchen table, you need a specialy constructed fricking gaming board, and where do you put it , when you are done with playing? Hello.
Besides, grown men feel a bit uncertain to be putting such vast numbers of toy soldiers on the table and then you even play with them, what if an attractive chick sees you? You loose your cool status forever. With other companies and 40k it's easier to pretend those 10 models are just randomly standing there and you are just having a friendly chat with your friends.
Time, I mean you need at least 2 hours, sometimes even more, a lot more to finish the game. When I still used to play with my son, we had to make a break for a night and continue the next day, while all the models stayed there on the giant gaming board. And how many gamers can afford to spend so many hours just for one game? And then you call for a rematch? Sorry, I won't have the time. I'm gonna have a quick match of malifaux with another mate during my coffee break.
Painting, so how many hours do I need to paint the 2000 points army. I mean days, sorry I wanted to ask , how many months? Who on earth spends months to paint just one faction to be able to play the game? No wonder malifaux and warmahordes are popular, you need at most a week to paint those 10 models.
Rules, omg I need to buy a separate book to play this, and it has 200 pages, and then I have to memorise all that? and on top of that a have to buy a separate army book, with hard covers and luxuriously illustrated, and I have to follow the forums to see what has changed in the rules, because they are constantly changing and then you even tell me that in 4 years all will be obsolete and I wil have to buy a new edition? Which will cost me twice as much and still the rules will be broken, because it's the concept of the WHF to create unbalanced factions, because the company in this way forces people to buy constantly new everything? Otherwise nobody will wan't to play with me.
Maybe I would better check the latest rules for my MTG deck and download them online for free.
No gaming community forum, that's something every other company has. That's probably becasue, they don't really care what the people who are buying their products really think. Which means I just lost 10 minutes of my life typing this, because those that would need to read it, won't.
Which basically means that the statement that they are primarily the miniatures company is valid, but in a weird way. The rules and the concept are outdated and anachronistic, let's buy some cool models from them, paint them up and call it a day.