- I've generally avoided Apple's own, as they tend to overcharge for most of their adapters/cables; except where their's is the cheapest or only one available.
- Of course there are some cheaper or more expensive examples of each of these, but generally these are good enough for rough price estimates.
And that's also the reason why you really can't compare it to the docks. These separate items you list are cheap and use cheap components such as Realtek NICs. If you look at the components OWC lists for their dock you can see that they are not using such components but the more expensive A-quality components. Theirs include an Intel NIC you'd also find in computers like a CAD workstation. You need to factor the (sometimes big) difference in quality of the components into the comparison as well.
With macOS there is yet another thing one needs to account for: drivers. With all those cheaper components you most of the time have to download a driver and install it. In some cases this is not an issue at all as the driver is easy to get and the quality is perfectly fine. That is not the case for some other pieces of hardware. The more expensive items use higher quality components that are supported by macOS out of the box which means you don't have to install a driver.
The other thing you are not considering is the pricing for Thunderbolt 3 hardware from Intel. The TB3 docks are priced much higher than the TB2 equivalents (about $100 in general). It seems far more likely that either Intel is asking more or that the TB3 technology in general (R&D, implementation, certification, etc.) has a higher price tag. Remember, this is technology capable of driving everything over 1 cable including charging up to 100W; there are a lot of regulations concerning power stuff so it wouldn't surprise me that it is actually this part that has driven up the price tag quite a lot. USB-C in general doesn't seem to be very cheap.
And lastly there simply is the factor "ease-of-use". People do want to pay for things like that and manufacturers know that.
If the sleeping issues are not at least partly a problem with the dock design, why did my first two have issues where as my third one handles external and computer sleeping flawlessly, and never randomly loses hard drive connections (including with the FW chain?)
If the issue is due to the dock design then why are there so many anti-hdd-sleep apps dated back prior to 2011 (aka the pre-Thunderbolt era)? If the issue were the dock then why does the sleep issues with external drives concern Windows, Linux AND macOS?
The problem here is that manufacturers started adding sleep options to the controllers of the external drives and these controllers have caused numerous issues with disks not waking, computers not waking, etc. WD has been very well known to have this issue as well as Toshiba. Google it and you'll find plenty of information on it.
Where do you suggest finding "real reviews"? I'm sure what you are saying is right about Amazon, and while I try to read tech site reviews to learn about features, not many professional reviews include long-term outlook.
Sites like Anandtech, Arstechnica, even 9to5mac to some extend. Anything but sites like The Verge, The Next Web, etc., basically any site that uses clickbait titles and writes articles that are no more than another copy of the manufacturers press release and specs sheet.
Or you could go old skool" buy it and use it instead of going through the entire internet to find every possible maybe-this-is-an-issue-or-I-am-just-being-picky thing there is. Warranty and quality has been better than in the past so I'd not be too worried about things like this. Long-term outlooks are non-existent because it doesn't make any sense to make those for most products (i.e. there are some for SSDs which only confirm the manufacturers calculations and many products are being replaced rather quickly by consumers (smartphones for one)).
I also really appreciate when a Manufacturer comments directly on negative reviews, attempts to address the issue, and then the customer follows up with a comment or edited review of the experience, as it reassures me in that Maker's commitment to their customers.
There has been some research into these kind of user reviews and it wasn't a very positive outcome. It basically is fraud on a very large scale (one good example of that would be the Dash app which, after being caught, was removed from Apples app stores; on a Dutch techsite this has also happened quite a few times). Companies go through great length to influence the outcome of the reviews by rewarding good ones, suing the negative reviews and even buying positive reviews from specialised companies.
When I see something like the above it actually raises a red flag. I only pick out small parts regarding things like someones workflow because it is very hard to fake those kind of things plus that's also the most meaningful of any review (how someone uses it). Sites like Anandtech, Arstechnica and 9to5mac (to name a few) show you how something can be used which most of the reviews do not.
