I really dislike this constant caveat that people keep placing against SV. "Well it isn't a problem outside of SV!" I keep seeing this appear in comment after comment on this article
That too, but also, a lot of us outside the valley have to deal with the unfortunate consequence of everyone looking towards SV as the "trendsetters" or sort of the ones who set the "meta" for "modern" software development, if you will, especially since most major confereneces are out in SF/SV area. At my own company, directors and above take frequent trips out west.
What this all boils down to, is if SF/SV is going to be seen as the beacon of software development, it is almost worse to me if it is ageism is being exemplified there. To give a rather rough corollary, consider if Washington D.C. never hired another underrepresented group, such as females, or minorities. It's sort of like, "well maybe I halfway, sadly expect that to happen in some small town somewhere", but C'mon! D.C.! Everyone's looking to you!" -- Same kind of thing.
Maybe, but maybe it's less pronounced? It's hard for me to say, as I've only ever not lived/worked in SV (hello from North Carolina). But FWIW, I am 43, and I don't feel like ageism has been a problem for me. I just went through a job search and had no problem landing a new gig in short order.
OTOH, to be fair, I am obsessive about learning new stuff, and I've been working with some "trendy" stuff the past few years (all big-data, hadoop, storm, kafka, etc. stuff) and I've been doing a lot of machine learning / data science MOOCs over the past year or so. So my skills are a good match for what there's demand for. But that would be valuable if I was 20, 30, or 80.