I've worked with hundreds of engineers who held various degrees. I'm always confounded by the lack of skill in the area of written communications. You can't get a degree without writing hundreds of papers. I can't understand why a professor would give a passing grade if the student can't express themselves. I've known people with Masters degrees that could not write an understandable paragraph even with the help of spell check and grammar assistance.
I'd say the problem is twofold. Besides the lack of communications skills you mentioned, far too many engineers, and for that matter other people with lots of technical expertise, assume everyone else is at their level. Yes, I'm guilty as charged. I've had conversations with laypeople where they might ask me a simple question, and within 2 minutes I see their eyes glaze over as I'm explaining things using technical terms which are old hat to me, but might as well be a foreign language to them. One of my favorites was when a customer wanted something which gave 100 watts of light. I assumed they might 100 watts of light energy, so I posited various solutions, including about 500 watts of metal halide, 400 watts of LED, etc. I also started going into luminous efficacy of the emitted spectra, CCT, and CRI. In the end just wanted to replace a 100 watt light bulb, but being an engineer if someone says 100 watts of light, I assume they mean 100 watts of emitted light, not 100 watts input. This is but one example of epic fail in the way engineers communicate with everyone else.
I have a theory that many software engineers came to the field because they are socially inept and therefore poor communicators. It's more comfortable to work with machines than it is to interact with people. We were not geeks because we programmed; we were programmers because we were geeks.
Not a software engineer, but probably guilty as charged. I recall some mandatory parties from back in my freshman year where I ended up being a wallflower the entire time, not saying one word to anyone there, and then leaving wondering what the point of the entire thing was. Yes, I've made plenty of friends before, but being in social settings with 100% total strangers is and will always remain very awkward for me. I imagine software engineers are even worse in that regard. The amazing part is a lot of these people actually go on to get married and raise families. How they meet people and nurture that kind of relationship boggles my mind because it's something I never was able to do. You have to "sell yourself" in a manner of speaking to do that. A lot of engineering types couldn't sell beer on a troop ship, that's how bad they are, including me.
A good engineer recognizes his/her shortcomings and makes up for them. That's why there is a specialty known as a "technical writer" who writes specifications and documentation. A good businessman should have the same awareness of his/her shortcomings.
Assuming you have the staff that's true. Many of these online companies consist only of the engineer, and maybe a small amount of support staff (i.e. assembly workers, shipping clerks, perhaps someone to handle orders). There's often no money to hire someone to improve communication. I've occasionally dealt with vendors on Alibaba. More often than not, I get communications from their staff asking me a question which are unintelligible. Here's a perfect example (I left out the person's name):
i am **** ****, you buy our led displays throught aliexpress store, I saw you confirmed order delivered. Glad to know you have got the item. Hope you will like it. now, have a question need contaction with you , the" one digit 7 segment 0.32 inch yellow color led numeric display, led digital display, 7-segment led display" and green product, these product's SPEC have wrong, havn't material, so can't make to you , i am sorry for that ,but we have other same product, please see the email file, if it is usefully for you.please tell me that is ok? please make sure to me, i wait you.
Note that they didn't even send me anything, and yet they said I confirmed "order delivered". Even more scary is that it appears this person's job is solely to communicate with customers.