I wonder what the "Doctor Who has become a parody of itself" looks like...I mean, was it all supposed to be very serious? I've lost count of how many times River Song retconned her story arc.
A partial explanation since it would take all day and all night, at least to explain.
Franchises like Star Wars and Star Trek have coherent fictional narratives. Even soap operas that always change backstory, do so in a manner that is somewhat (at least) plausible (although unlikely, granted) and expands the narrative, rather than openly dismisses it.
Star Trek established a different timeline that expands rather than contradicts the show's history
Not all ST fans care for it, but it at least respects the continuity.
Dallas and Dynasty had many changes over the seasons, but those changes were in the attempts to expand the narrative. Dallas was an outlier, in that the dream season was a choice to dismiss a disastrous season and reset the narrative. The exception to the rule.
I am not sure that River Song retconned her story Arc. In a show about time travel, there is some flexibility, and even so, RS had knowledge of the Doctor's past and future, so she was in a unique position to advance and expand the narrative. Moffett was the first showrunner to address time travel distortions, contradictions and more detailed scenarios on a larger scale. It expanded the narrative without contradicting it. Granted not everything was clear, but it was dealing with somewhat underused scenarios, surprising for a show about time travel. "Day of the Daleks" "Mawdryn Undead" "Trial of a Time Lord" "Father's Day" and Multi Doctor Stories were the best approaches up to then.
I was not a fan of the McCoy era and the Cartmel master plan, but it expanded the narrative without destroying it.
The assertions that the Doctor had a dark, mysterious past was explored, but the basic continuity of the narrative remained intact.
No"fact" was established that contradicted over 20 years of continuity at that time.
Chibnall introduced a false origin story, and multiple elements that openly contradicted over 50 years of continuity
If Chibnall is to be believed, the Doctor is never in any real peril since he can regenerate endlessly.
Matt Smith's Doctor's speech to Clara when he thought that he was in his final life was one of the most powerful events in the series
It now doesn't matter according to Chibnall's version
Chibnall 's approach seems to be that anything goes, ignore everything that happened Hartnell to Capaldi, that it didn't matter
When a series has no foundation, no continuity, etc is no different from a silly sitcom where it is just the foolishness of the week
That undermines the entire series
I could talk endlessly about the content post Capaldi/Moffett, the horrendous writing and directing (many if not most writers and directors had little or no sci-fi background), the horrible casting and the loss of millions of fans but that has been mentioned extensively in many places.
JW and Gatwa - horrible casting choices, the scripts increasingly prioritized silliness and identity politics
There is a HUGE difference between expanding a narrative and contradicting it
Chibnall has openly contradicted it, and the show has been in a downward spiral ever since
In one story the Dalek is defeated by sticks and stones? Contrast that with the Eccleston Dalek story when a single Dalek is destroying everything right left and center
Sutek, arguably the most formidable adversary in the series history defeated by a dog collar? "
Just two examples of the show becoming a parody of itself
Literally everyone I know who watched Doctor Who has a similar view