The data is already on the blockchain, new dapps could show your history and implement your past posts, doesn't mean you will need to repost them again or that doing so is okay just because you're using a new dapp, imo. The difference could be if they are rewarding you with their own token, then just accept that but not hive rewards and repost at your heart's content.
Think of it this way, a new dapp could easily also do something similar to cross-posts on peakd; "hey everyone this comment we placed here under your old post will create a new post on our dapp and show that post but the difference is that everyone can re-vote it now, whether or not the same people we don't care". This is the same amount of effort that reposting is. If you want to repost for the attention/visibility/growth of your following/new autovotes, etc, then do it, just don't accept curation as post rewards for something you've already been rewarded for (doesn't matter if curators didn't find it at the time cause you were new or whatever, as I said in a post somewhere earlier in a comment the post itself is proof you've put effort into finding curation, followers, etc). A better comparison would be with some youtube channels that take weeks to generate new content, if Kurzgesagt suddenly reposted a video from 3 years ago without saying anything I'm sure people would be like wtf? Even tho it's just adrevenue money going to it that doesn't affect any viewers or youtube shareholders - here it does, it's inflation that could go to others who are putting in the effort to post new content that hasn't been posted yet and that's what the Hive consensus wants/is in agreement of, originality and fresh stuff. Either way not really sure how else I can explain this but I'm pretty sure the majority of stakeholders would be against this no matter through what dapp if it's about Hive curation rewards.
Happy new year.