I must admit, I don’t know Rebol, but this suggests to me it’s not so simple.
I guess technically there are a few languages simpler than Smalltalk, but they’re so obscure they’re hardly worth mentioning. Rebol, for example, is so obscure, it doesn’t even register at TIOBE nor IEEE Spectrum.
And Rebol is used in a very, very narrow niche. How many commercial Rebol users are there? I bet you can count them on your fingers! ;-)
On the other hand, Smalltalk has many commercial users around the globe. You can count as major users the likes of JPMorgan, Desjardins, UBS, Florida Power & Light, Texas Instruments, Telecom Argentina, Orient Overseas Container Lines, Siemens AG, and so on. Check out ALLSTOCKER and ATMs in Moscow streets.
Cincom and GemTalk are major Smalltalk vendors. Does anyone provide commercial support for Rebol? Many enterprises are reluctant to go with a language that has no real support. Would you have them turn to Rebol user groups???
Rebol development appears to have stalled. It’s been dormant for more than 3 years!
But Pharo is still very actively being developed. Version 6.0 is due later this year.