The Republican Party is a "brand" like Coca Cola or Chevrolet. Use our brand name, follow our rules.
Each side evaluates the terms, BEFORE agreeing to follow them. That is basic contract law.
So the Donald decided the advantages outweigh the disadvantages, as did the RNC.
Considering post WWII history, from George Wallace, Ralph Nader, Ross Perot, John Anderson, Pat Buchanan, etc. both sides made wise choices.
Cuz 3rd party dooms it to failure, which the dems have learned better up until now.
Nice to see the Republicans act wisely for a change.