The "at scale" problem affects a tiny proportion of sites. So the question is collapse into what? Depending on which stats you use the next most popular CMS is either Drupal or Joomla with less than a tenth of the install base. Neither of those are going to replace Wordpress. According to https://whatcms.org/Tech_Reports more sites use Wix, Shopify and Squarespace than Drupal.
Here's what you do. Go to this site and put your sites name in the input: https://whatcms.org/
See if he used a free Wordpress theme. If he did, you probably were hustled. A deadbeat buddy of mine you to have the same MO, didn't stay in jobs long, spoke a questionable game, and basically slapped together free wordpress themes that he'd sell to people/friends for hundreds if not thousands of dollars.
I found links in your comment that were not hyperlinked:
I did the honors for you.
^delete ^| ^information ^| ^<3
In my experience, developer from Spain are a different category than from India.
No sane developer on UpWork would claim that their skill level is below requested.
It's hard for a non-technical person to evaluate a portfolio.
To identify a CMS, you can use https://whatcms.org, - that gives you a first impression.
Analyzing a GitHub repository is harder, there are some flags to pay attention to (is there a README file? How's the comments, are there any comments?)
Some of my clients hire me as Lead Developer to find them a cheap developer. It takes a while, but mostly, eventually we find someone to take over the task.
It usually takes around 5 hours, but it saves you a lot of money in the end.
Feel free to contact me.
While that's true, it's not worth modifying your robots.txt
to remove the wp-admin entries. There a lot of other ways to detect that a site is on any given CMS, like the Javascript files it serves. whatcms has a list of the metrics they check to determine the platform.
Use https://whatcms.org to check the CMS.
The advantage of WordPress Multisite is also that all the cms updates / maintenance happens in one place. And there are loads of security and reputation problems with unpatched cms out there.