Except that is a cop-out. Lambda is a cheat. GR is wrong anyway, since QFT is right. Like fighting over the scraps left over from Newtonian physics. SR/GR is classical ... if Lambda explains everything, why are theoreticians and experimenters looking deeper?
Lambda was a 'fudge factor' when Einstein inserted it in order to get the static universe he assumed and was ignored after Hubble, and only in light of the discovery of accelerating expansion has it been revived. It's not meant to explain
anything, it's descriptive
, and the research is to determine if it actually does have a value, what value it has, and if it's non-zero, why it's non-zero. I really shouldn't have to explain this.
You're also incorrect in saying GR is wrong and QM is right -- if Quantum Field Theory were right and General Relativity were wrong, then QFT would already be a theory of quantum gravity, and it is not.
GR has yet to be invalidated by an observation -- all we can say is that we know where it breaks down, not that it's incorrect. And what we know is that both
of them give nonsensical answers when they're combined. What's most likely is not that either one is wrong
, but that both are incomplete
, just like Newtonian gravity was incomplete. That incompleteness didn't make Newton useless: we still don't need anything more than Newton to calculate the flights of every spacecraft we've ever launched. Using Einstein would only make matters unnecessarily complex, and the additional couple of decimal places gained would be irrelevant.
Whatever theory manages to combine GR and QM is going to have to duplicate their results at sufficiently low energy levels, with considerable accuracy, because we have already measured both those theories with considerable accuracy, and it doesn't matter if it's string theory, M theory, or something no one has come up with yet. Both GR and QFT are approximations, but they are deeply and profoundly accurate approximations, and any unified theory has to be at least as accurate as both.
Keep in mind also that 'dark energy' and 'dark matter' are just labels: they don't explain anything either. They mark the place where researchers have observed something, and don't know what it is yet, but they know something is there. There's nothing wrong with placeholders in science -- those are the things that need further observations and research, after all.