BOSTON — “Man, it must be cool to be in this type of environment every night.”

On Friday night, the Boston Celtics, who are bad, played the Philadelphia 76ers, who are even more bad, and not in the cool, Shaft-kind of way, either. Sitting in an almost-full TD Garden that eventually filled to its 18,624 capacity, a Philly beat reporter couldn’t help but remark in amazement.

He is accustomed to sitting in the mostly empty Wells Fargo Center, home of the lowly Sixers. He has visited Atlanta, where the playoff-bound Hawks play before preseason-caliber crowds. Yet in Boston, where the Celtics’ greatest accomplishments are unlikely to come until this season has ended, fan support remains high.

This is going to sound corny, because it feels corny to write, but it’s past time to give a nod to Celtics fans, who have done something not many fans of teams in the Celtics’ position would do: They have shown up.

The Celtics’ sellout streak ended this season, which is not surprising. After five years of championship contention and one year of irrational optimism, the Celtics did not run from the term “rebuilding” the way some other teams have. Only 17,130 showed up to watch the Celtics top the Utah Jazz on Nov. 6, the first time in 289 games the Garden wasn’t sold out.

The next home game, however, the team announced a capacity crowd of 18,624. Three months later, in a Super Bowl Sunday matinee clash with the Orlando Magic, a legitimate sellout crowd showed up to watch two teams essentially grapple for position in the NBA draft lottery. All told, the Celtics have sold out 20 of their 39 home games, and the building has been more than 97 percent filled on average, despite the team having lost 54 games and counting.