Articles you linked are fairly old, unofficial (that is, don't represent opinions of Red designers and developers) and are written by more-or-less experienced Rebol users. That is, it's hard to talk objectively when you have a tunnel vision accumulated over time. These languages are great, and deserves all the praise they get.
As for shortcomings and limitations, here I can speak only form my experience. If you want an open discussion about it with other developers, consider to visit our community chat [1].
"No dependency" goal - whole toolchain is written from scratch and heavily relies on a native functionality provided by underlying OS. This is cool and ambitious, but there are problems:
* developing a compiler on a par with existing state-of-the-art (e.g. GCC or LLVM) ain't small potatoes. Currently there's no optimization layers, and emitted code might left much to be desired. Perfomance of Red/System IIRC is 2-3 times slower than C (again, without any optimizations). Red is 6-7 slower than C.
* As I said, emitter and linker are written from scratch, and signature of compiled binaries doesn't match common ones, which leads to Red toolchain and compiled applications being flagged by AV vendors as a "generic malware". [2] Language adoption suffers because of that, users are baffled, and vendors don't provide a single clue on how to resolve this issue. It's an uphill battle.
Implementation details:
* Red is its own data format, and structure of this format might be considered as sub-optimal by someone - each value is represented as a boxed structure 4 machine pointers in size. On 32-bit systems that's 128 bits, on 64-bits 256, but can be squeezed down to 160, AFAIK.
* Red/View strives to provide a set of native widgets supported across all OSes, which means that more sophisticated widgets (e.g. tables, Android-like swithes, tree-list) ain't included in the box. That doesn't mean that you can't implement custom version of them - but this process isn't trivial and requires some experience.
* Red is currently limited to 32-bit. As stated in the blog post, 64-bit support will likely come next year, but will require a dedicated rewrite of runtime.
* Compiler and R/S toolchain are written in a closed-source (and officially dead) Rebol2, which is a no-go for FOSS enthusiasts. Self-contained Red toolchain executable relies on Rebol SDK, which requires a paid licence which is not selled anymore - this means that no one can build Red toolchain as the one provided on official website by themselves. This isn't critical, as you can always use code in repository to compile from sources, but, well, there's a fair share of nay-saying here.
User experience:
* Learning curve is steep. Documentation is being worked on, but lefts much to be desired, esp. if you are a programming newbie. We compensate it with strong community presence though.
* Obviosuly, decision to go blockchain generated much controversy and became a major source of gossips. Crypto community is highly polarized: toxic brain-dead speculators on the one side, and extremely smart, dedicated individuals on the other. The former cause us major pains and headaches, the latter keep inspiring us to keep going.
* We also get a lot of harsh critics regarding a pace of development. People go as far as to say that "development is frozen", without considering all the details. Currently there are 12 team members, before that there were 4-5. Rebol never became a mainstream, so it's kinda hard to search for experienced employees, capable of writing production-quality code and contributing to the main development branch.
Your criticism has a point, and I do agree that we need to post more objective, real-world examples in the main blog, and also mention language limitations and short-comings from the designt standpoint.
I also agree that bold claims about Red being easy to pick up are largerly unfounded, albeit serve as a good PR bait.
[1]: https://gitter.im/red/red
[2]: https://news.ycombinator.com/item?id=18348938