yes grappeling is being less and less effective. but to have the best understanding of takedowns you got to have practice doing the takedowns as well as blocking them. But both are needed to be able to have the best defense.
chuck liddell has a wrestleing background so he knows how to do good takedowns which helps him defend because he knows what the other guys thinking.
im sure silva and franklin also have jiu jitsu and wrestling backgrounds.
it was bound to happen after the world was shocked by jiu jitus and started learning about it and analyzing its weakness *lots of people probaly hated how average royce dominated*
just because they dont got a belt from a gracie *or anyone* doesnt mean they dont practice it.
being well rounded is the key to being a champion. there is always a chance that it will go to the ground and when it does thoes grappeling skills will come in handy even if your just going to ground and pound.