Cybersecurity certifications are a wonderful way to learn and grow with your career.  In fact, the "gold standard" the CISSP®,  is used globally as a basis for hiring high level positions.  One of the main reasons CISSP® is the gold standard is due to its tight control over the question bank.  Allowing remote testing opens a Pandora's box for cheaters and scammers.  It would allow people to:

1.  Use VGA/HDMI splitters to send signal to another room
2.  Record Questions
3. Distribute Questions as "dumps".
4. Utilize a proxy to take exam for them.  
   
   

Remote testing increases the possibility of exam impersonation, exam answers being passed through side channels  and exam question exposure.  The last one is the killer - questions are expensive and they are the bread and butter of ISC2 certifications.  Losing control over this is a massive business risk. 

There have been several very well respected exams/vendors that have had issues with integrity as of late.  In order to not be inflammatory I will not list them.  

Here is a relevant article on the CREST certification having this issue though:
https://www.theregister.com/2020/08/14/crest_investigates_ncc_group/

Another Article about CEH:

https://www.fox13news.com/news/investigating-cyber-security-at-u-s-central-command

Ultimately, remote testing could diminish any ISC2 certification to the point where it may not be viewed with esteem due to the very high probability of fraud.