Earlier quoted context omitted.
Absolutely not. I had, and still have, my own small business in Poland and I was clear (in writing) that I am planning to visit my main client.
You mentioned both employer and client, are they the same?
Differences, in Poland at least, are that small business owner in this scenario is not protected by employment laws (3-months notice layoff, max 3 months salary-equal damages liability etc) and uses company's (EU)VAT registration number instead of personal social security number equivalent (PESEL number). It eases abroad contract agreements, invoicing and allows serving more clients easily. Company existence can also be validated on EU VIES[1] website quickly.
In the visa case, I have of course used the "paper" phrasing as in reality I was, and am, only employed by my own small business.
[1] https://ec.europa.eu/taxation_customs/vies/#/vat-validation