If the Champions League were only for European teams, there wouldn't be teams from Israel, Kazakhstan, and Azerbaijan.
I think you are wrong about this, its not because they are from Asia, but because of their football association under UEFA:
Israel: The Israel Football Association (IFA) became a full member of UEFA in 1994.
Kazakhstan: The Kazakhstan Football Federation (KFF) became a full member of UEFA on April 25, 2002
Azerbaijan: The Azerbaijan Football Federation (AFFA) became a full member of UEFA in 1994.
Source:
https://www.uefa.com/nationalassociations/ISR/https://www.uefa.com/nationalassociations/KAZ/https://www.uefa.com/nationalassociations/AZE/while, Saudi Arabia till now under AFC, So, it is normal that many people do not agree if Arab team enter the UCL.