this view seems to be the current belief from everything I have been reading lately. The last time I was researching AAS (2008ish) if you even considered running anything without test you were labeled as an idiot. The argument is convincing enough...anavar only will shut down your testosterone production, so in a sense you are replacing your naturally produced anabolic with a synthetic and thus shouldn't expect much more in the way of gains than what you are currently able to do...especially considering how effective testosterone is when compared to var.
really interested to see more comments on this as I am starting to believe the old "test must be used on every cycle" is broscience myth. Test will shut you down the same as var, so couldn't you just take more var to enhance results? It wouldn't be cost effective but some people are less concerned about that than others.
And also I know this question was specifically asked about anavar but consider other orals as possible effective stand alones, dbol or tbol as examples.