Being able to configure and set up the own ham radio station, being able to copy a SOTA activation and be copied by the activator up to completion of a QSO is a challenge that I'm pretty sure nost of us like and enjoy. It's what the technical aspect of ham radio is about and it's always been.
From this point of view, it may have no or little interest for a technically motivated ham the copy and contact of SOTA activators by using SDR systems and remote stations in which configuration and set up they have not contributed at all and they would only be a user of those third party means.
At the same time, we all know and it's fair saying that ham radio is and has always been enjoyed differently by different hams and despite of that, we are all hams, no matter the aspect of the hobby we like and we play most.
As every other human created activity ham radio is in constant evolution and nowadays hams may enjoy doing and studying different things and aspects of the hobby like, for instance, comparing and studying how a given signal from a SOTA activator is received by different SDR stations located in different points of the planet during an activation. This may be an interesting field to study propagation behaviour and nobody can say this is not technical enjoyment of ham radio too.
I've never used SDR to receive but I know I've been chased by hams using SDR to copy my signals and all I can say is I don't mind at all. Just the contrary, I'm very pleased to hear them and being chased by them as often as they want/can.
They have fun chasing us activators and we, activators, have fun being chased by them. That's all it counts for, 2 x having_fun_hams.
Imagine one day when we are activating and our log has only 3 stations. After CQing for long minutes with no response in a cold summit and running out of time, battery, XYL patience or whatever you want to say, we finally get a call from a ham who is copying our tiny QRP signal through a SDR, we then complete the QSO and we, activators, have finally and luckily qualified our activation with the 4 necessary QSOs.
What's the problem with that fourth contact being with someone copying us through SDR?
None, I think.
The purists may say there should be a different category for those using SDR and remote stations, but others could also ask a similar thing right now with respect to hams being unemployed or retired because they have much more time to enjoy the hobby than those having a full time job, family, children, dog, one hand only, one leg only or anything you can wish to consider.
Being SOTA a non competitive activity and being it only a hobby and a challenge to eachoneself, I can't honestly find any arguments to deny any hams their right to enjoy playing radio by chasing SOTA with the help of SDR or remote stations, no matter where they are located.
I say this while stating that I've never used a SDR for a QSO. Neither SOTA nor any other.