The answer to the question "Why is the media ignoring my favorite team" is almost always: They aren't. There are 30 teams in the NBA, almost everyone has at least something interesting you could write about going on. Some teams get more coverage than others for sure, because they are bigger drivers of "clicks" but the Celtics are actually probably in that group themselves, but overall if it feels like there isn't enough C's coverage its because there are 29 other teams to cover and you can only write an article about the c's being dominant so many times.
There has been plenty of Celtics coverage this year. Everybody has done a pod about Tatum for MVP. Everybody has done a pod about the C's offense. There have been a bunch of articles about the c's good vibes. A ton of article or discussion about the Jays being the best duo in basketball. Ect, ect