Agreed, although with the rover lifetimes, especially on more recent ones, I think they know that the rover will last way more than a few months.
It just looks a lot nicer to politicians and the public funding them if they say that the rover that was supposed to last months lasted years than if they say the rover was supposed to last 5 years and lasted 5.1 years. Plus, both politicians and the public lack the ability to adequately follow nuance, so "our rover which was intended to last 15 years died after only 9 years due to a global dust storm" would not carry over as well as "our rover which was intended to last 6 months died after 9 years due to a global dust storm".
Even with just the InSight lander, every other rando loves to chime in with criticisms that brushes should've been included to wipe the panels as if NASA wasn't capable of thinking of that.
kidding aside...the discoveries made from rovers Perseverance, Opportunity, etc have been phenomenal!
Factor-in that they were only expected to last a couplefew months ... whoa!
Imagine how much more will be learned with rovers expected to last years!