The job of people allegedly 'banking' on finding unrelated crimes had their job made a whole lot easier by seemingly everyone surrounding Trump having a contempt for telling the truth, lying to investigators, lying to the public, lying to Congress. You can call them "process" crimes all day long, but they are crimes for a good reason, and when an organization (the campaign and transition) decides that it's not important to tell the truth under oath, and about stuff all around the edges of the core issue - Russia "collusion" - and when there are many BIG money links between members of the campaign (including the Trump family) and Russia, then the job of establishing a plausible case for an investigation was made for them.
The Russia tower projects, plural, are a perfect example of all this. Trump said dozens, maybe hundreds of times, he had no business deals in Russia - Russia..what? Russians who? Then we find out he had TWO active deals being pursued during the campaign, one of them ongoing with very serious people with very serious money and connections right into the Kremlin (as any big project like that would have) until AT LEAST election night. That one was supposedly worth up to $300 million to the Trump Org. It's really unthinkable that kind of thing would NOT be investigated, especially when seemingly everyone around Trump was knee deep in Russians and ALL OF THEM LYING ABOUT IT.
That's the context, and a small part of the context, for these so-called "process" crimes.
You mention Flynn. We have an incoming NSA for goodness sake lying about his lobbying work for foreign governments. He knew better, and it's really unthinkable to have a person in the position of NSA with connections of money and peddling influence that he's hiding from government officials and the public, and Trump supporters are dismissing that as a "process" crime. I mean, he'd only have access to the most guarded secrets in the U.S. government. Is it too much to expect for him to disclose to the government AND THE PUBLIC his foreign connections while in the private sector?