Once upon a time, in an ancient land, there were album credits. Big round vinyl LPs had inside sleeves or booklets on which everyone involved in the making of that record was named. Not just every last writer, musician, producer, and recordist, but even A&R, booking agents, legal people, etc. Lyrics too! When CDs came along, that got trimmed a bit with the smaller format and certainly became less enjoyable to read the tiny print. Now that the vast majority of sales are digital, I would think a resurgence of credits is in oder. After all, the cost of crediting and linking to everyone’s websites is so minuscule that it hardly bears mentioning. Instead, the opposite is true. I really don’t know why, but I do know that itunes has a policy of not accepting credits and external links. Same with Amazon. This is very bad for people like us.
If you’re reading this then you are involved in making music in some way and you want your name to appear on your work. It’s good for your spirit and your business. It’s also good karma to credit folks who contributed in obscurity, often for little or no money. Links and linkbacks help people find new music and learn about you and what you do. Perhaps you like the drumming on some record. You find out who the drummer is, follow them, find other things they’ve done, and so on. There’s no downside that I can see. As for itunes’ policy, I can only assume that it’s a human resources cost thing. Also they want people to stay on their site and not be lead outside by links or distracted by credits.
I encourage everyone who is making and selling music to steer people towards bandcamp.com, tunecore.com, your own website, or any other sites that support credits. Furthermore, when you make your layouts and design your sites, include full crediting and links! It’s the right thing to do and it’s good for you.