If I pull plugs, new plugs go in. Same way I am not draining transmission fluid to send in a few ounces for used oil analysis, pour it through a coffee filter in the funnel, back into the transmission. Same thought process for changing the oil filter with the oil. Bizarre that some people will change the filter, not the oil, and just top off because the bottle of oil claims XX,XXX miles. Or changing the oil, but not changing the filter, because filter advertisement claims XX,XXX miles. Some people drain radiator fluid, then pour it back in through a funnel with a screen.
Not just reading it online. I have seen all this in real life.