The gist of this story is that the T-14 project failed due to technological limitations. An additional perspective circulating is that T-14 funding was at least partly influenced by patronage and that Russian tankers were not particularly enthusiastic about it.

Excerpt from Putin's Wars (2022) by Mark Galeotti:

Civilian factories...often actually have more political muscle than the generals...

A particularly good example may be the much-hyped new T-14 Armata tank. Back in 2015, on the fringes of a particularly dull military colloquium in Moscow..., I got the chance to share a drink with some officers from the Kantemir Division. More formally the 4th Guards Kantemirovskaya Order of Lenin Red Banner Tank Division named for Yuri Andropov, this is one of the elite 'palace guard' units based around Moscow...

The conversation, inevitably, turned to tanks. The 4th was equipped with the T-80U, but that year it was announced that they were going to be one of the first to receive some of the 2,000 T-14 tanks the Defence Ministry was going to buy from Uralvagonzavod. The T-14 is the first truly new-generation Russian tank, a supposed marvel of modern electronics, with an unmanned turret mounting a fully automated, high-power 125mm 2A82-1M gun, and an armoured capsule within the main hull for the three crew. How excited were they about this? The conversation followed what I found to be the familiar trajectory when a nosy Brit starts asking these kinds of questions. First, the official line: that this was an honour, that the Armata was the most advanced tank of its kind, that it was a mark of the prowess of Russia's military technology. But after a while, a more nuanced perspective emerged. Was it just too expensive? Was it needed? Above all, was it just too advanced, potentially too finicky for the real battlefield?

Although to an extent this is a carry-over from the days of the Second World War, when rugged but simple Soviet vehicles often were fixed in battle with all kinds of field expedients and the expertise a driver might have gained repairing a collective farm's combine harvester, there is nonetheless some truth to the proposition that Soviet vehicles were quick to break down, but also quick to get moving again. What about the T-14 Armata, with all its fancy, solid-state electronics? The fear was that when it suffered anything more serious than a thrown track or a jammed gun, all that could be done was trundle it back to a specialized repair depot. It was, they concluded, not so much the tank the army needed, but the tank Uralvagonzavod wanted to sell them.

While the T-14 looks impressive on paper, Uralvagonzavod is a major employer, and in 2011, when Putin was facing angry protests against his re-election, a foreman from the tank production plant at Nizhny Tagil offered to come to Moscow 'with the guys' to deal with them. It became something of a media sensation, not least as it played to the Kremlin's efforts to portray the protesters as middle-class elitists, out of touch with 'real Russia'. The foreman, Igor Kholmanskikh, was later made a presidential representative, and Uralvagonzavod got the Armata contract. Putin knows to reward loyalty.