You're confusing a cover letter with a table of contents.
The letter you keep saying isn't a subpoena is the letter that was sent along with the subpoena. You're right about it not being a subpoena, but your wrong to conclude that it's existence is evidence that there is no subpoena.
There's nothing to gain by sending a subpoena letter without a subpoena, but if that were to happen, the person who received the subpoena letter wouldn't argue that the subpoena was unlawful (which is what's happening).
I am not confusing anything. Its existence is not evidence there is no subpoena, just like the fact that Gary Busey likes green apples is not evidence the subpoena doesn't exist either. The fact that no one can produce it is evidence of the subpoena not existing.
I explained what was to be gained already. They wanted to give the appearance of moving forward officially without giving the office of the president or the Republican minority in the house the ability to produce their own evidence and subpoenas. Solution, fight the battle in the media politically and just SAY you issued subpoenas. It satiates their ever more hysterical extremist base, optics work to their favor, and since it is not official the Republicans can't exercise due process in a non-existent process.
There's nothing to gain by sending a subpoena letter without a subpoena, but if that were to happen, the person who received the subpoena letter wouldn't argue that the subpoena was unlawful (which is what's happening).
That is EXACTLY what is happening. If it were a real subpoena they would still have to enforce it in court. The way to prove that argument wrong is to bring it to court, but you can't use a request for information as a legally actionable subpoena, because it doesn't meet the requirements for action. I can give a toddler some crayons and tell them to write me up a subpoena, and I can call it a subpoena, that doesn't make it a subpoena. The law defines very explicitly what an actionable subpoena consists of.
here are the requirements for a subpoena to be actionable:
https://www.law.cornell.edu/rules/frcp/rule_45PRODUCE THE SUBPOENA FROM BEFORE THE OFFICIAL VOTE