The Americans with Disabilities Act (ADA) was first passed in 1990. Twenty years later, the US Department of Justice released an update called the 2010 ADA Standards for Accessible Design. These standards cover the design of physical spaces and have been interpreted to include web locations as well, so it can be difficult for the would-be accessible website designer to use them.
This guy is right on! You should learn new skills that are critical to your success instead of focusing on your business. Just making a website is easy, making one that is easy for your users to navigate, captures your users' interactions, feed that back to a CRM so you can act on it and setting up automation to handle each one properly so you don't lose the customer is not. (And do not forget, the design of your site is critical to the effectiveness of Google and Microsoft Ads. Without them, no one will ever see your new, beautiful site.)

The ADA itself holds different organizations to more/less stringent standards based on a host of factors, government funding being a major one. Government agencies themselves are usually held to the most severe standards. That said, while ADA has adopted WCAG as the defacto standard, from what I’ve seen it appears they’re going with AA compliance as the most reliable one. That said, we’ve done work with some organizations who’ve chosen to comply with AAA in an effort to be as buttoned up as possible from an accessibility and experiential perspective. We’ve also worked with some who have tighter budgers and aim for level A compliance and have a more “react and repair” mindset when they discover anything in their site that is giving someone hardship from an accessibilirt standpoint.
The debate over the Americans with Disabilities Act led some religious groups to take opposite positions.[32] The Association of Christian Schools International, opposed the ADA in its original form.[33] primarily because the ADA labeled religious institutions "public accommodations", and thus would have required churches to make costly structural changes to ensure access for all.[34] The cost argument advanced by ACSI and others prevailed in keeping religious institutions from being labeled as "public accommodations".[24]

Certain specific conditions that are widely considered anti-social, or tend to result in illegal activity, such as kleptomania, pedophilia, exhibitionism, voyeurism, etc. are excluded under the definition of "disability" in order to prevent abuse of the statute's purpose.[8][9] Additionally, gender identity or orientation is no longer considered a disorder and is also excluded under the definition of "disability".[9][10]
Shortly before the act was passed, disability rights activists with physical disabilities coalesced in front of the Capitol Building, shed their crutches, wheelchairs, powerchairs and other assistive devices, and immediately proceeded to crawl and pull their bodies up all 100 of the Capitol's front steps, without warning.[38] As the activists did so, many of them chanted "ADA now", and "Vote, Now". Some activists who remained at the bottom of the steps held signs and yelled words of encouragement at the "Capitol Crawlers". Jennifer Keelan, a second grader with cerebral palsy, was videotaped as she pulled herself up the steps, using mostly her hands and arms, saying "I'll take all night if I have to." This direct action is reported to have "inconvenienced" several senators and to have pushed them to approve the act. While there are those who do not attribute much overall importance to this action, the "Capitol Crawl" of 1990 is seen by some present-day disability activists in the United States as a central act for encouraging the ADA into law.[39]

The Department has assembled an official online version of the 2010 Standards to bring together the information in one easy-to-access location.  It provides the scoping and technical requirements for new construction and alterations resulting from the adoption of revised 2010 Standards in the final rules for Title II (28 CFR part 35) and Title III (28 CFR part 36).
Once you have been hired and started work, your employer cannot require that you take a medical examination or ask questions about your disability unless they are related to your job and necessary for the conduct of your employer's business. Your employer may conduct voluntary medical examinations that are part of an employee health program, and may provide medical information required by State workers' compensation laws to the agencies that administer such laws.