There are multiple ways a runner deck can bring the game to a point where all corp decisions feel meaningless:
1) Resource denial: the corp has no money, cards, and as such does not have the means to claw themselves back into the game and interact meaningfully.
2) Lock: the corp has a set of win conditions and the runner has effectively countered all of them.
3) Super efficient rig: The runner is running efficiently enough that it is not practical to tax them out.
4) Building up to a combo that you can't stop: The corp's cards don't really matter, they are just hoping they can win before the runner goes off.
5) The runner deck and/or pilot is just way better than the corp deck/pilot
If you are the corp, if you are in any of these situations, it can feel pretty miserable, and you are liable to blame the runner's deck for putting you in this situation. You might not actually have a very good game of Netrunner.
But before labeling a deck as uninteractive, you need to consider two things:
1) No deck is uninteractive in a vacuum: what about the corp build meant that they had no meaningful ways of interacting?
Netrunner is a really beautiful game for a lot of reasons, but one of them is that most corp decks have counterplay to anything most runner decks are doing, even if they didn't specifically prepare for the matchup. Considering the example of Clanarch, the fact that more or less every corp deck has ICE to protect HQ means you have some counterplay. Considering the example of DDoS + False Echo combo (Dyper), the fact that you have ICE means you can at least throw minor speed bumps in the way of the runner going off.
And that's really great and all. But if you go up against another deck and you are still thinking "goodness, I wish I had more ways to interact", the next time you are in deck construction you can think about other cards you can play to make the matchup better.
If after all that you still don't feel like you have any meaningful decisions, yeah, the deck is uninteractive.
2) Does the runner deck fundamentally rely on cutting off all options to the corp, or did the game feel uninteractive just because the runner was winning?
Runners have inevitability in Netrunner. If the game goes on forever with nobody doing anything, runners will eventually win when the corp runs out of cards or likely, way before that, they draw too many agendas to reasonably manage. Also, runners have inevitability in the sense that eventually, they will amass so much money and install enough cards that they will be able to run everywhere, steal everything, trash everything.
People also build runner decks with the hope of shutting down corp win cons, and with the hope of overcoming corp roadblocks and preventing the corp from preventing the runner from winning the game. There are a lot of ways to do this: resource denial, tech cards against strategies you expect to see, a nice efficient deck.
But if the runner is able to accomplish these goals too well, you might be in for an uninteractive game. I've account siphoned you to zero and can keep on recurring account siphon long enough that you'll never be able to realize your win condition before I've realized mine? While I may have built my deck with the hope of achieving such a game state, there are things you could have done to stop me, but now that we are here, yes, the game is uninteractive.
To expand on this point, people often build runner decks with the hope that they will reach these uninteractive game states and there is nothing wrong with that. When you build your runner deck, you aspire to have answers to everything, whenever you need them. But if the runner can answer everything you the corp can do, that means things may not be very interactive. It's the corp's responsibility to keep this from happening.
All that being said, there are different runner plans, and some offer a corp more glimmers of hope than others when they are winning. Sometimes that is even false hope... the corp thinks they are still in the game when they really aren't, but that false hope can be enough to keep a game exciting. Current Clanarch is not a deck that offers you a lot of hope if you are getting absolutely crushed.
It is 100% true that being siphon-locked to death before a 15 card R&D dig feels very uninteractive. Personally, if I were thinking about bringing a deck to a casual event, I wouldn't bring it just because I know that if things are going well, my opponent might not have a lot of fun.
But I would also say that asking if an individual deck is interactive is the wrong question, because no deck is interactive or noninteractive without considering the deck it is going against and the two pilots.