Just curious but who are the etiquette experts in Germany and the Netherlands who advocates this? I did a google search for European etiquette experts and repeatedly found examples of the American etiquette icons of Post, Baldrige and Miss Manners being referenced in articles about European etiquette. It would appear that American etiquette experts are defining what is good etiquette beyond the borders of North America.
I'll be turning 30 next year (as will by husband). Were we to just sit around and expect someone else to throw us a party, not only would there be no party, but our friends and family would be surprised and disappointed, wondering when we lost our generosity 
(Yes, if you organize a party, you pay for everything, you truly host your guests and no gifts are expected, even though there are likely to be some, smaller, token gifts from close friends)
However, in the article by Miss Manners and the book by Letitia Baldrige I referenced earlier, neither really mentions the gift grabbiness of an adult hosting their own birthday party but rather the focus is on the host/honoree being the center of attention. How are the fundamental principles that Baldrige and Martin are espousing not applicable to everyone, regardless of culture? If people host their own birthday parties but not for others, how is that "looking outside" oneself? Regardless of the culture, it is still emphasizing a self-centeredness to bring attention and honor upon oneself while failing to extend honor and attention to others. Particularly if birthdays are so important to people that they feel compelled to host their own parties...why, oh, why haven't friends and family taken notice of this and stepped up to honor the person with a party they *know* will be appreciated?
And to be honest, it doesn't surprise me that selfishness and attention grabbing can be inculcated into a culture and thus become acceptable. Selfishness is the path of least resistance as opposed to the harder task of stepping outside oneself to serve others, to be humble in focussing the attention away from oneself onto to others, and extending the effort to honor someone. To "honor" requires action and merely sending "honor vibes" on someone's birthday doesn't cut it.
I'll be doing a more thorough search on German sources next week, as I'm off to celebrate my husband's birthday with his parents and grandmother

No, we're not throwing a party this time around, I just baked a cake we're taking alon and his mom has asked grandma to come over for coffee and cake on Sunday, as usual.
I did have a quick look at Knigge, which is the best known German etiquette book and it does mention making invitations for birthday parties, and it seems those are meant for your own party.
But, as I said, I only had a moment to look at this and since I find it really, really interesting, I'll be looking into it with more detail later on, and I promise I'll report back with whatever results I get.
It would seem to me that the point of view simply is different. A party I'd host on my birthday would not be seen as being all about me but as being my way of treating my friends and family to something nice. It's not thought as me honoring me, but as me honoring those who've been with me....
Naturally selfishness is not seen as something positive over here. It just is demonstrated in a different way and many very selfless people would be embarrased if someone else went through all that trouble to organize a party. THAT would feel like taking advantage of others. (I know it's not, but as it's not customary at all, it would feel like that to many).
I really have a feeling that this is more about customs than selfishness, things can be done in many ways and there are many different ways to be gracious, selfless and appreciative of others. Telling my parents and inlaws that I'd love to take them out for dinner on my birthday to thank them for having raised me and that amazing husband of mine does not seem selfish to me. Having my grandma-in-law ask me over on her birthday and serve me yummy little sandwiches and champagne to celebrate life doesn't seem bad.
To add: it would appear rude and quite cheap of me to my friends and family, if for my 30th birthday I did not organize anything.
Yes, it'd be seen a little self-centered if I kept throwing huge parties every year. But the mile-stones, if I didn't do anything it would be regarded as weird at best.
I'll be back with a more detailed (and hopefully better formulated) answer later.
Oh, btw, as hubby and I have birthdays really close to each other, would it be different if we each host a party for the other one? Only happening to take place on the same day *grin*
Edited to add and clarify