Actually, the divestment of the USMC M1A1 tanks is a political and a budgetary decision. One has to read the Defense Blogs consistently to understand the reasons why.
General Berger, Commandant of the USMC, predicted that Congress would not increase the Corps budget for modernization, and in reality, the USMC didn’t ask for $10USD more to modernize, nor did Congress increase the Marine’s budget either. So the Corps had to divest in Legacy vehicles, artillery, and rotorcraft to save money, and General Berger did say that the Corps did indeed save money doing this, but he didn’t say how much, nor did he say where the saved money is going towards.
One funding area is building new US Navy Light Amphibious Warships (LAWs) that will cruise around INDO-PACOM with 75 Marines aboard and their JLTVs and light vehicles. There is controversy in this too as LAWs are only armed with a single 25mm Mk 38 Mod 2 autocannon and a few machine guns, and thus very light armament with no Anti-Air, Anti-Sub, and Anti-Surface missiles—Defense analysts were quick to call this out.
So the US Marine Corps wants to use ATGMs, HiMARS with Anti-ship missiles, drones, loitering munitions, and more armed UAVs to counter enemy armor from far away. If the concept will work is anyone’s guess as I can’t seem to fathom Marines lugging 100 loitering munitions onto an island to fire at 100 enemy vehicles. But loitering munitions can fly in from dozens of miles away so the concept might prove useful instead of getting tanks onto the islands and slugging it out with enemy armor—attack them from above with cheap drones and munitions.
Do I think that the USMC still needs tanks? Yes, I do, because like at Ft. Knox, the USMC have bases that require an armored vehicle to get in the way as a roadblock to any type of assault, both foreign and domestic. Tanks garner respect, and no one dares attack the Gold Repository at Ft. Knox because there are US Army M1A2s and AH-64s stationed nearby on call to help.
The USMC could benefit from buying the MPF Light Tanks with Active-Protection and ERA. Yes, it would be a very dark day if any CONUS USMC base gets attacked, but as the US Capitol Insurrection showed, sometimes a tank is definitely needed to defend a base and repel whatever invaders crash through.