According to Michael David Smith of Pro Football Talk, the NFL confirmed the NFC East team submitted a proposal suggesting the teams alternate between home and road games on the holiday. They later withdrew it.
The proposal said, "to continue the annual tradition of having Dallas and Detroit play on Thanksgiving, provided that one of those clubs host a home game with the other club playing away, and alternating home and away games each subsequent season."
Smith noted the Eagles likely withdrew the proposal because it didn't have a chance at passing.
The Cowboys have played a home game on Thanksgiving every year since 1978, while the Lions have played in Detroit on the holiday every year since 1945.
On the surface, the Eagles' decision to fight against a set home game for their division rival makes sense.
After all, the outings come on short weeks, and staying at home allows players to keep their normal schedule and enjoy the holiday. The road teams often have to travel across the country on an expedited timeframe, and their minds could be elsewhere.