It is an article of faith in American journalism schools, almost as powerful as the belief that the byline is the most important part of the story, that that as a conjunction should be extirpated in copy.
And today on Facebook pops up one of those typical lists of advice, "8Words to Seek and Destroy in Your Writing," recycled from 2012. That is inevitably among the eight, though I will grant that the writer, Robbie Blair, is more nuanced than most, but it is still the sort of article that invites oversimplification in practice.
You are probably aware that I have touched on the subject before. From a post in April, after someone at the national conference of the American Copy Editors Society who should have known better listed that as a pet peeve:
Item: That can be safely omitted when it links two short clauses, as in the hypochondriac's epitaph, "I told you I was sick."
Item: Even the Associated Press Stylebook knows better than to eliminate that promiscuously:
"That usually may be omitted when a dependent clause immediately follows a form of the verb to say: The president said he had signed the bill.
"That should be used when a time element intervenes between the verb and the dependent clause: The president said Monday that he had signed the bill.
"That is usually necessary after some verbs. They include: advocate, assert, contend, declare, make clear, point out, propose and state. ["Usually necessary," for Fowler's sake; these are idiomatic].
"That is required [!] before subordinate clauses beginning with conjunctions such as after, although, because, before, in addition to, until and while. …
Item: If that introduces one of two paired subordinate clauses, it should introduce both, to cue the reader to the parallelism: The president said that he had signed the bill and that enforcement of the act would begin immediately. The reader will not consciously notice the parallel construction, but it will smooth their path.
Bryan Garner writes, "The writers who ill-advisedly omit that seem deaf to their ambiguities and miscues."
Americans are addicted to easily achieved self-improvement, but you cannot achieve sophistication and nuance in writing and editing by following ten-things lists online, or relying on the dangerous oversimplifications of Strunk and White.