It is impossible to discuss this topic without addressing the legality. The Internet Archive operates in a perpetual gray zone. While it champions the public domain and fair use, hosting full series of copyrighted content like Dora the Explorer or Go, Diego, Go! is, strictly speaking, copyright infringement.
The specific appeal of finding a "full series" on the Archive is rooted in the fragmentation of modern streaming. While current hits like Blue's Clues & You! or PAW Patrol are readily available, the back catalog of Nick Jr. is riddled with gaps. nick jr full series internet archive