Survey for Social Media Accessibility

Vicki W

I have a close friend who is the Senior Social Media Strategist for a large New York firm who deals with multiple national commercial accounts. She is an advocate for improving accessibility to all social media platforms and has done a great deal of research into this subject. She will be giving a presentation to not only her marketing firm, but many of their clients on March 15 concerning issues around social media accessibility.
Below are some additional questions she has. She is seeking information from those who use the below platforms. Answers need not be extensive, but concise.
Anyone interested in contributing to her presentation and relaying accessibility concerns to her clients, please comment on the below questions and which of the listed platforms they affect by February 27, 2021.
Send your comments to me at the below e-mail address and I will copy and paste them to a new e-mail and send them to her. Your names or any other personal information will not go to her. Please send them to me and do not post them to the list. 
Thank you.
Here is my e-mail address and below that are the questions. Please put the word "survey" in the subject line.
Are the following social media platforms accessible? If not, why? Is it the platform limitations? Are publishers not taking advantage of alt text capabilities? Something else?
1. Twitter
2. Instagram
3. Facebook
4. LinkedIn
5. Pinterest
Thank you.