whoever is using transaction fees as an excuse for not being consistent with his DCA is only trying to create excuses for himself and not looking for solutions to that short termed problem of transaction fee. Like you've said, the majority of us sometimes leaves our funds in exchanges for weeks pending when the fees will be more convininece for us before sending it out to a more secured wallet. It's not like you're unaware that it's unsafe to leave your funds in an exchange it's just the normal process you will get to experience as long as you're doing your DCA.
I think you are quite right, Transaction fees are not something that someone should take into account when they have implemented DCA. One reason I like DCA because we are consistent in routinely buying Bitcoin, regarding expensive withdrawal fees, of course there is an option to withdraw it once a month from the Exchange used.
What is the worry of transaction fees because it will not change anything in the view of DCA because looking at the current situation we can even see that even though the transaction fees after halving there were some uncontrollable moments but in the end now the transaction fees are back to normal and even look very comfortable to use anything.
Things like this will not be a reason for someone not to do DCA because after all, many of the excuses used are only one of the reasons for those who are not serious about investing so they look for their own reasons not to do it such as transaction fees that are too expensive or the classic reason where they say the price of bitcoin is too high and it's too late to be in it.
Whereas if they are serious about doing it regardless of the price when the goal is for the long term then everything will look as planned especially since the current btc progress is still very good and the future prospects still look bright. although we cannot know the future but of course reflecting on the historic past then there is nothing wrong with staying in btc to support the future.