WASHINGTON — The president of the United States appears to believe that you don’t matter unless you are on television. By that measure, Robert S. Mueller III’s 10-minute soliloquy seemed to have seized his attention.

But even though Mr. Mueller, the special counsel, cut through the legalese of his 448-page report on Wednesday to make clear that his investigation in no way exonerated President Trump, he stopped short of delivering a punchy sound bite to summarize his inquiry. Mr. Trump has had one for two years — “No collusion! No obstruction!” — and recently had White House aides print the slogan and hang it on his lectern.

Mr. Mueller’s refusal to pass judgment on whether the president broke the law is one example of how the special counsel operated by rules ill fitted for the Trump era. He said nothing and the president said everything. He worked in secret, allowing the president to fill the void with reckless accusations of a witch hunt. His damning conclusions were encased in dense legal jargon that the president distorted into a vindication.

Mr. Mueller seemed to expect that the system would work as it had in the past, with Congress or perhaps voters making the decision about whether Mr. Trump had committed a crime, only to see the president’s handpicked attorney general — and Mr. Mueller’s longtime friend — make his own determination that there was not enough evidence to support such a charge.