I’d argue that most mainstream FOSS is extremely strong. Something like 80% of servers and 60% of smartphones run Linux. Up until recently, Cloudflare was using Nginx for their entire CDN. The thing they replaced it with is technically also FOSS. Probably most computers in the world are using OpenSSL or GNUTLS.
I think the real “weakness” of FOSS is that they don’t have the money or the desire to schmooze corporate decision makers. They also don’t have sexy GUIs, but anyone could contribute that if they wanted.
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