Can't really agree with this as a general statement. While it surely is possible to damage the seals, they are quite easy to remove. If the bearings have replaceable cartridge bearings then OK, let them crap out and replace the bearing unit. But not all are built that way and the OP needs to figure out the details of what is on the bike and then decide.Yes things have changed. Most bearings on a bike these days are sealed. You risk damaging the seal trying to remove, clean and repack the bearings. You are better off running those bearings until they wear out and then replace.
Well designed bearing systems (whether cartridge or not) typically will be able to go a lot longer before service than the OP's 2,000 mile intervals.