I mean, today we even have special amphibious APCs and tanks that don't need any landing craft to transport them on, was there really no "instead of putting people in that boat, put a tank in it and let the machine gunners have fun with it, until it shoots them with a cannon" idea? And lack of artillery support seems at least strange, considering that the british Royal navy had a bunch of otherwise useless battleships they built a long time ago.
The overall performance of Duplex Drive tanks in the American sector was underwhelming, many sinking when they turned perpendicularly to the beach and their canvas skirts were overtopped by rough waves.
| Operation | Unit | Embarked | Launched from Landing Craft | Landed Directly on Beach | Sunk While Enroute |
|---|---|---|---|---|---|
| Overlord (June 6, 1944) | 13th/18th Royal Hussars (Queen Mary's Own), 27th Armoured Brigade | 38 | 32 | 5 | 3 |
| Overlord (June 6, 1944) | 1st Canadian Hussars, 6th Canadian Armoured Brigade | 40 | 30 | 10 | 5 |
| Overlord (June 6, 1944) | Fort Garry Horse, 10th Canadian Armoured Brigade | 40 | 0 | 40 | 0 |
| Overlord (June 6, 1944) | 4th/7th Royal Dragoon Guards, 8th Armoured Brigade | 40 | 0 | 40 | 0 |
| Overlord (June 6, 1944) | Nottinghamshire Yeomanry (Sherwood Rangers), 8th Armoured Brigade | 40 | 0 | 40 | 0 |
| Overlord (June 6, 1944) | 741st Tank Battalion | 32 | 29 | 3 | 27 |
| Overlord (June 6, 1944) | 743rd Tank Battalion | 32 | 0 | 32 | 0 |
| Overlord (June 6, 1944) | 70th Tank Battalion | 32 | 28 | 0 | 5 (Four lost when landing craft sunk) |
The 58th and 62nd Armored Field Artillery Battalions (two of sixteen such separate units to fight in the ETO) equipped with M7 Priest self-propelled howitzers came ashore in LCTs to support the initial landings of the 29th and 1st Infantry Divisions, respectively. The LCTs were configured so that the carried vehicles could fire their howitzers at the beach for twenty-five minutes (H-30 to H-5) from a distance of 8,000 yards before they were to proceed to the beach to unload at their designated time (H+90). The LCTs carrying the DD tanks of the 741st and 743rd Tank Battalions were to operate in a similar manner until they reached their release point.
Gunfire support from ships offshore commenced at H-20 and ended just as the first troops landed to prevent friendly fire; support resumed 30 minutes after H-Hour when the Naval Shore Fire Control parties had been landed and gained their bearings. The destroyers USS Satterlee, Thompson, and Harding moved very close to the shore and provided direct gunfire support to the Rangers who landed at Pointe du Hoc, and the USS Corry was sunk by a German shore battery or a mine while providing support for other units.
In Europe? To some extent. In the pacific? Not at all. Starting off with D-Day, there were obviously the Sherman DD's as well as Hobart's Funnies early in the landings. The largest shortcoming of the landings on the American beach heads (I can't confidently speak for the Commonwealth beaches) was the use of the Higgins boat. The drop front left men without any cover charging into the open much like the movies and the boats provided little fire support. However due to the availability of these boats combined with the Army's lack of experience in amphibious landings, the men horribly suffered.
In the pacific the story was different. In May of 43 with the start of the Aleutian Islands campaign, marked the USMC attempting their first amphibious assault on a fortified beachhead.
The marines initially wanted to use relatively new LVT's which allowed them to drop marines on the sand and then provide fire support, with later models having a 37mm, 75mm, and multiple .30cal machine guns, as well as allowing them to reverse back into the water. However the Navy insisted on the use of Higgins boats. The marines realized from scouting missions that the Higgins boats would get caught nearly 200yds from the sand on the coral and the men would have to wade through water under fire. The navy was stubborn and wanted to use boats but the marines refused to land without use of LVTs so they compromised and the first two waves would come in on LVT's and the last 2 on Higgins.
Lo n behold the troops in the LVT's made it to the beachhead just fine suffering minor casualties and the troops in the Higgins got the short end of the stick to put it lightly.
After that the navy conceded and the marines went ahead and expanded their LVT fleet. While the LVT's were extremely popular, their role as fire support vehicles was slowly phased out as it became easier to land proper tanks like Shermans which could resist Japanese anti tank fire.
EDIT: And artillery support usually ceased when troops got within 3 miles of the beach due to fear of shells falling short of their target. A pretty harsh lesson learned in WW1 when artillery accidentally shelled your own troops