[M95D]

I think the author missed one of the most important points: genetic variability to obtain the minimum viable population.[1]

Let's say they make a perfect clone of an extinct animal. It can't reproduce by itself. It needs a mate. Let's say they clone a second animal of the other gender. Let's say they reproduce (low chance of that, but let's say they do). All their descendants need mates too, other than their siblings, otherwise it leeds to inbreeding.[2]

They need dozens if not hundreds of different individuals to make a viable population that doesn't go extinct again.

[1] https://en.wikipedia.org/wiki/Minimum_viable_population [2] https://en.wikipedia.org/wiki/Inbreeding_depression

[Nasrudith]

Technically that could be overcome if you don't care about individual specimen welfare and mutate until you get viable specimens. It won't be quite the same but it would restore a viable species.

[M95D]

> mutate until you get viable specimens

Mutations are very rarely viable. In fact, the original cloned animal mutations must be eliminated in order to have viable future generation. The only thing that (may) benefit from mutations is the imune system. See the problem with cheetah's lack of genetic variability: https://en.wikipedia.org/wiki/Cheetah#Genetics