If this argument was as solid as you say, then all routine checks would be pointless.
I don't know about traditional blood testing, but a permanent implant which checks HR, pressure, glucose, temperature & oxidation would be pretty useful, not necessarily to diagnose anything, but to provide data for doctor when patient has actual symptomps.
They kind of are. Spain doesn't have yearly physicals, and during a GP visit, they don't even take your blood pressure. Blood tests are extremely uncommon, unlike in British medicine, where they take your blood pressure every time and blood tests are so prevalent people usually request one from time to time despite having no symptoms. Spain's example showed the above (or the lack of) doesn't increase all-cause mortality and even excelling in longevity statistics.
https://www.rieti.go.jp/en/columns/a01_0455.html This japanese article found "No clear-cut evidence exists to determine whether undergoing health checks leads to greater longevity and/or lower medical expenditures."
Several published papers agree. There is in fact little evidence to support regular checkups if you’re asymptomatic.
https://pubmed.ncbi.nlm.nih.gov/31642821/
And blood pressure is especially pernicious, basically every doctors office measures it wrong so the results aren’t particularly useful. Many use the wrong size cuff for example, or don’t give people time to relax before a reading. A ton of people have white coat hypertension, high BP only because they’re in a doctors office.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1120072/
I saw a paper that showed only 36% of cardiologists did it right.
Math does indeed make for solid arguments. If you want to make a counterargument then you have to address their math, which you didn't.