Guests have been a thing since I have been following the sport. The only difference is, back then it was very rare that a rider would be missing unless they were genuinely injured.
Mike Coles, Phil Morris, Brent Werner, Neville Tatum, Colin White and Jan Pedersen were all regular guests for Newport in 1999 when Anders Henriksson and then Frank Smart were out injured. It has always been the case.
What gets on my nerves is when riders are apparently injured, then ride in Sweden on a Tuesday and then are unfit to ride on a Wednesday for their British club before riding in Poland on the Sunday.
There are only two solutions to stop all this. Either pay what Poland do OR ban any rider who races in Poland. Sadly, either option looks about as likely as Manchester United winning in Munich this evening!