Not sure why this bothers anyone. Horford has been banged up and not himself until recently. For all his talent, Tatum hasn't been consistently as good as the guys who did make it. And clearly, Hayward isn't back to his old self. I don't think any Celts got snubbed.
OTOH, others did get snubbed. Doncic is clearly an all star. Laughable to omit him. Just as it was a joke to omit Jokic last year.