I think instead of telling other people what to do or not to do ("Carry your backpack! Don't use luggage transport!") it might be better to simply explain why one personally thinks it's a good idea to carry a backpack on this journey, so that potential first timers get an idea why that might be something that, as strange as it sounds, could make their journey even better and not just more difficult, exhausting and uncomfortable (as one might expect).
The thing is that many people who decide to walk the Camino have never done any hiking or backpacking before and are used to travel the "traditional modern way" with a suitcase. And not like a hiker with a backpack.
You tend to stick to what you know. If you've always travelled that way, of course you'll ask yourself, "Why should I carry a backpack when I can have my suitcase with all my nice stuff waiting for me at the end of the day?". It seems unnecessarily difficult to reduce your belongings to a few items and then carry it all day on top of that. When you've always enjoyed your travels with a suitcase, why risk not enjoying carrying a backpack?
When I watch some of my family pack for travelling, even if they're only going to be away for a few days, they pack in a way that they'll have everything they'd have at home, too. You'd need two donkeys or a lot of servants to carry all that stuff! And they're convinced they absolutely need it all!
For someone like that, even reducing their gear to one very heavy 70l backpack and then sending that forward would be a giant challenge.
They simply don't understand that it is possible to travel with less and they're convinced it must be a horrible, uncomfortable experience, and those who decide to carry their own backpack must be crazy extreme-hikers. Which is as much a prejudice as the other way around, with some of those who carry their own packs pointing fingers at those who don't...
Personally, I am convinced that there are many things to be learned by reducing the things you bring with you to an amount you can comfortably carry in a backpack every day. Especially when you find it difficult to reduce to less things to bring.
I am also convinced you won't know what you'll learn from that exactly, unless you actually did travel that way (and did actually reduce the weight of what you carry to a comfortable amount and didn't just torture yourself by packing everything you usually put into your suitcase(s) into a giant monster of a backpack).
For me, personally, giving my backpack to someone else simply won't happen. It is my home away from home. Like a snail or tortoise or maybe a hermit crab.
I've got everything in there to survive (comfortably!) for a few days even if I do not find accommodation or a restaurant.
It is my house, my bed, my closet, my fridge and kitchen, ect. ect.
When walking, it doesn't feel like a burden, it feels like a part of me.
There's a freedom to be found in having everything you need with you at all times that I, personally, find very appealing.
I'd feel less free and would enjoy my walk less with having to choose beforehand where I'll stay the next night, organize pack transport, and then having to walk there no matter what happens only because all my stuff is already there and dictates what I have to do that day.
When I carry my own pack, I can stop whenever I want to.
Tired? Stop after just a half day and rest.
Enjoy a place you just walked into? Love the atmosphere? Just stay there instead of walking to where your luggage stays.
Made friends who stay in a different town than you planned to walk to, but you'd like to spend more time together? No problem, you're free to stay with them, and not where your luggage dictates you have to stay at.
Feel a pain somewhere in your legs or feet, or a blister forming...? No problem, just stop and check into the next albergue to rest and relax, no need to take a taxi to where your suitcase stays.
Feel oh so strong today you want to try to walk that very long day? No problem, just walk and stop whenever you feel like it.
Ect.
When you have luggage transported, you'll reduce yourself to a smaller variety of places to stay at (because some do not accept luggage transport, or a backpack max but no suitcases).
And even more importantly, whatever happens, you have to walk to where your stuff stays, even if you feel tired, have injured yourself, got to know people you'd prefer to have dinner with that evening and who stop somewhere else, fell in love with a certain town you just walked through, bad weather conditions (heat, storms, torrential cold rain all day) ect. Or you'd have to use a taxi to still get to your destination despite injury ect.
For me, personally, that would take away much of what I enjoy in my travels.
But that's just me and what you prefer (or need) might be completely different, of course.
But maybe this helps to at least understand a bit better why some people enjoy walking with a backpack, and that there's no need to pity those or make fun of those who do carry their pack. I've often been made fun of because of my big backpack, how much of a torture that must be... Just no. No it isn't. It's my home and my freedom, and I love to carry it.
(For those who simply cannot carry a backpack it is a whole different story, this is for those who could easily carry a backpack but wonder why they should).