This is often the position of tire manufacturers, which is driven largely by lawyers limiting the company's liability exposure, but in reality it's not true. I was told the same thing by my Porsche dealer about the tires on my Porsche Macan GTS. When I asked at my local tire shop, the owner said they patch the tires all the time and owners continue to use them without problem for the life of the tire.
What was the source of your information?
Michelin has an excellent "Michelin Promise Plan" for new tires (not OEM supplied tires on new cars) that provides free flat tire replacement or towing up to 150 miles to the nearest approved Michelin dealer of your choice.
I recently received the following after contacting Michelin.
"The Michelin Promise Plan includes a 3-Year Flat Tire Changing Assistance. for every Michelin passenger and light truck replacement tire sold in the U.S. on March 1, 2011 and after.
A qualified service professional will replace a flat tire with the inflated spare. If an inflated spare tire is not available, towing will be provided at no cost (up to 150 miles) to the nearest approved Michelin dealer of your choice. Flat Tire Assistance is available 24 hours a day, 365 days a year in the U.S. and Canada.
As of June 1, 2019, this program has been expanded to include fluid delivery (gas, water, etc.), lock out service, battery jump start. *Consumer is responsible for the cost of delivered goods. There is no additional cost for this change.
This program does not does not apply to original equipment tires.*
The Flat Tire Assistance phone number is 1-888-553-4327."