I think someone was smart enough to limit img sizes in the code (if Proboards isn't doing that automatically these days?). That's a 3000 px wide photo (you should see that it's pretty huge if you right click and view image) and there's no scaling code that I'm using (I just used Flickr's generated code here).
I do want to note that if everyone just relied on the auto-code to scale their photos down, it could really suck for people who have slow connections or limited browser cache.
I hate Tinypic's TOS, so I never use them- I love Flickr to bits. I usually don't use their code generators, because it's faster for me to just type code- but, I think most people would like their ease of use (and Flickr's TOS actually dictates that you use it- heh). The free account is probably plenty large for most casual users, but, it's worth it to me to be a paying member.