Any undeniable reasons for collection of dead specimens?

[thomaseverest]

In short, absolutely. This has been discussed quite a bit on other threads.
https://forum.inaturalist.org/t/pros-and-cons-of-specimen-collecting/25115
https://forum.inaturalist.org/t/non-invasive-naturalism-thank-you/27717

@kseniiamarianna

I would think that, in case of lizards, taking very detailed pictures and taking a DNA sample (for example, a tail, a toe, etc.) should be enough. I know about holotypes, paratypes etc., but isn’t it a bit of a thing of a past, when you needed to bring the physical object itself in order to prove that you have seen it?

Maybe for lizards. But for a vast amount of invertebrates, dissection is needed for species IDs. DNA is only so helpful unless it can be correlated with morphological traits. And so often there are physical traits that are missed the first time around. Being able to revisit specimens (say under a microscope) is the whole point of having types.