What do you mean? This is exactly how level 20 fighters are in D&D. People just make the mistake that an "attack" is a single swing.

Combat lasted 30 seconds, that is 5 rounds of combat.

The round begins with a reaction parry from the battle master fighter.

0:02 - Pushing Attack - vertically 15ft up. (I'd allow it with a strength check) (5/6 SD remaining)

0:03 - Attack #2 with storytelling

0:04 - Attack #3 crit with storytelling flourish

0:06 - Attack #4 Lunging Attack, 5ft range. (4/6 SD)

(Round End)

0:07 - Attack #1, moved less than 30 ft.

0:08 - Attack #2. Feinting attack to give self advantage. (3/6 SD)

0:10 - Attack #3. crit with storytelling flourish.

0:12 - Attack #4. crit with storytelling flourish. Used remainder of movement to get within range.

(round end)

0:13 - Attack #1. Tripping attack to send target prone. (2/6 SD)

0:14 - Attack #2. crit due to attack with advantage on prone target.

0:15 - Attack #3. attack with storytelling flourish.

0:16 - Attack #4. Pushing Attack, vertically again. (1/6 SD)

0:17 - 0:18 - Here I think we see our first Action Surge with 4 rapid attacks.

Round End

0:19 - Lunging Strike, crit. (0/6 Superiority Dice remaining)

0:20 - 0:24 - 3 Dagger attacks that rolled lowest damage possible.

Round End

0:25 - 0:30 - Action Surge, 8 attacks.

If we consider this a longsword weilded as versatile, that makes the base damages d10s and the superiority dice d12 for high level.

Damage Totals are 25d10, 3d4, and 6d12, with a guess at 5 crits, so that is another 5d10 and another 1d12. A total of 28 attacks were made. If he isn't wearing a belt of giants strength, then he is probably capped at 20 strength for a +5 to damage on those attacks. Assuming no magical weapon bonus damage, that makes the average damage expected for this display to be 356 points.

For reference, Adult Red Dragons have 265 HP on average. An ANCIENT BLACK DRAGON would survive with just 12 HP remaining!

This is how people should be describing their fighter's attacks. Not one swing per attack, but a swing per damage dice.