The issue is not whether Sendle is right for you, it clearly isn't and I don't think anyone here is contesting whether or not you had a bad experience (or 3) with them. I fully believe it, and I have heard plenty of other stories that certainly don't make me feel very confident they'd be a good alternative to Aus Post for me.

The issue is that you can't be authoritative about these kinds of things based on your experiences, and / or the experiences of those that choose to post their complaints elsewhere. You can, of course, choose what is right for you, but you can't choose what is right for anyone else, and imply sellers don't care about their customers if they don't adopt your personal preferences. If they (Sendle) are working well for a seller, no complaints from their customers, etc etc, then all this post is to a seller like that - if they even see it - is "I won't buy from you". This means you've announced yourself as someone who is not a customer of theirs, and if all their other customers are happy, why should they care about this post? To put it another way, sellers tend to make business decisions like using courier services knowing full well that it means some people won't buy from them, for various reasons. 

It's got nothing to do with defending Sendle and their associated couriers, like I said I don't use them and don't feel inclined to, and I know plenty of other sellers who refuse to use them as well, if just because they are a courier, as that entails limitations Aus Post doesn't. 

I for one did not intend to make you feel unwelcome, though to be fair I did not have any specific intention of making you feel welcome, either - I don't tend to put up the happy banners for anyone who posts, be they new or not so new, rather I just respond to the content of what they post, if I see something I want to respond to.