Affixing (TM) does not make something an enforceable trademark. Trademark rights are established by use of the mark in commerce. A (TM) is used to put others on notice that a word or design is being used as a trademark, which could potentially be evidence of the intent of an alleged infringer in a subsequent lawsuit. Intent is relevant because it affects damages and other remedies.
It's similar to creating a work covered by copyright vs. registering it with the copyright office.