Is it right to use a bare infinitive as a subject complement as in the following quote?
"Its true purpose is convince shoppers that your product is the preferred choice"
Another example:
"Their purpose is convince holders of political office of the importance of their industry but also to inform them about their expert knowledge and responsibility in their respective industry."
Sources:
http://www.businessessentials.co.za/2017/07/14/brand-toolkit/
http://www.serviceplan.co.kr/en/397.html
I am aware of that bare infinitive can be used when the sentence contains do as in this example:
The thing to do is [call for a taxi].