Personally, I think that the plain text url external chain should be useful, and I have been sending plain text urls, but I dare not be very sure, because I can't find the official affirmation of Baidu about this, and I have doubts over time. Today, I searched the "plain text url link" again and found Lee's reply post in Baidu webmaster club, Confirm that the spider will crawl the plain text url.
Baidu Club Lee's reply is as follows:
1. Text link URL address, Baidu will find that it is a URL address and use this address to grab the corresponding URL address
2. Our only criterion for judging whether a link should pass weight is whether the user or the other website sincerely recommends your website, and whether the recommendation is valuable to users.
PS： After receiving this confirmation reply, we will not feel that we are wasting time and hesitating when we send the plain text outer chain. However, we should pay attention to the quality of the outer chain and be valuable to users, because this is Baidu's only criterion for judging whether links should transfer weight.