Every company has finite time to give to support even if they heavily invest in it and people continually demonstrate how bad they are at basically everything. People treat emails to people they deem less important than them as asynchronous to be dealt with whenever and emails TO such folks as synchronous to be dealt with immediately. If not given immediate response they are liable to forget about it until its convenient for them to deal with it again and if the response is again not immediate they will forget about it again.
People's initial problem statement may be insufficient to even establish identity let alone nature of problem and solution. This is usually established by repeated follow up questions sometimes repeating questions to get the actual answer because it turns out they had no idea about the actual answer or indeed don't know what words mean.
Due to both of the above even simple issues are likely to become 12 step marathons with the associated cost of context switching to their problem 12 times. Worse due to the low cost of initiating an exchange they are likely to do so even when they could have resolved the issue in 10 seconds with google or even turning their head into the on position.
Your suggestion would turn a well funded support center into a team of professional shit shovelers trying to clean the Aegean stables with teaspoons.
An actual call queue intentionally and constantly drops matters too unimportant to invest 5-10 minutes in resolving and makes people do the whole shebang in one go by having them answer the follow up questions now.