I don’t agree with them. In 1862 Lee invaded the pro-Unuion half of Maryland and wondered why no one was rushing to enlist in the Army of Northern Virginia, and why no rebellion had broken out.
If they can see the strategy behind the Gettysburg Raid [I have trouble calling it a campaign], aside from gathering provender, giving Northern Virginia a rest, and frustrating any chance of Lee’s being sent west, more power to them.
The critical theater of war in the Civil War was the West. It’s where the Civil War was decided. And Lee either never grasped that fact, or deliberately ignored it in his desire to put Virginia first. Such parochialism does not a great strategist make.
Hmmmm.... a very curious term that: "Gettysburg Raid."
What do you call a "raid"?
Was Hitler's 1944 Ardennes offensive a "raid"?
Was Napoleon's march to Waterloo a "raid"?
Each involved the largest military force their countries could muster.
Each was intended as a war-winning knockout blow to their enemies.
Each was an act of desperation by an out-gunned army hoping to turn the tide of war.
Each was launched by men often considered tactical geniuses.
The failure of each campaign eliminated all future possibility of eventual victory.
As to which theater was more important, East or West, when Lee surrendered at Appomattox, the war was effectively over. Doesn't that answer the question?