Correct. Poisoned by it.
No not really more encouraged in that direction. As mentioned Brexit started in 1999 when Farage was elected to the EU and gained access to the media. From that point on he plugged anything he could think of into it including racism - always backing off from that but always making comments in that direction.
He'll freely admit that access to the media allowed him to do it.
The reason people see nationalism as advantageous is even more interesting. They always do when things aren't 100% as it's an easy thing for some one to blame. People don't like change and things have slowly in the very early 70's followed by much much more quickly. Obviously all down to the EU even though the same thing has happened all over the world except in undeveloped countries. Those are the ones that got the work.