The brilliance of last year's Ukrainian counteroffensive and its importance cannot be overestimated. The Ukrainians talked all summer long about the coming offensive near Kherson so convincingly that Russia moved troops there to meet it, leaving he northeast only lightly defended and no one in the Russian military or Russian intelligence had any idea what was coming. When the offensive began in the northeast instead of near Kherson and the Russians were routed from Kharkiv, it sent shockwaves through the Russian leadership and Russian military bloggers and even some hosts on state run TV and some have still not recovered. This was step one in convincing the Russians they have lost the war.
The Kherson offensive was already underway, but it was a different kind of offensive. Recall, the Putinheads said it had failed after 2 weeks, but it was never meant to be over that quickly. It was intended to push the Russians back across the Dnipro, and it was successful. And a strategic victory because it took away the route to Odesa, at least for the foreseeable future.
The Kharkiv offensive was an important strategic victory for Ukraine because it took away the main supply route from the Western Military District to the northern Donbas grouping (who were HQ'd in Izium). Voronezh is the HQ for the 20th Combined Arms Army, and the main hub for supplies and troops going to Ukraine.
When the AFU took Kramatorsk, they cut that supply line. That also meant everything coming from the training grounds in Belgorod and Kursk had to take the long way around to Millerovo. When you extend your enemy's supply line, you slow down the reinforcements and materiel coming to the front.
The supplies start at Voronezh. They can go west to Stary Oskol or south to Liski. From Stary Oskil they can go to Belgorod or Valuyki, from Liski they can go to Valuyki or Millerovo.
Without Kupyansk, there is no way to supply Izium, and the northern salient of the Donbas offensive failed. That was the northern half of the great pincer that was going to encircle the AFU in the Donbas.
The southern pincer began at Popasna, would run through Bakhmut to Sloviansk. and meet up with the 20th CAA from Izium. The JFO are captured, the war is won, etc.
When Izium fell, the great encirclement failed. The Putinheads coped by telling themselves that Bakhmut was an important strategic target and needed to be reinforced by the Izium group. That was about 7 months ago, and has apparently culminated with the heroic near-encirclement of Bakhmut.
What started as an "encirclement and capture" war was turned into a head-on, brute-force war of attrition- with Russia's greater mass pitted against Ukraine's better application of 21st century technology and precision fires.
That's what makes the Kharkiv offensive a strategic victory.