Long document full of legal language than can only be truly comprehended by those with Legal Training isn't at all the same as BIG FAT TEXT INDICATING IN A SIMPLE WAY THAT THIS IS NOT A PURCHASE.

Absolutely, in the absence of actual Pro-Consumer Regulatory Obligations, the whole "Agreement" is a valid way for sellers of digital media such as Steam to legally cover their asses and not actually saying to prospective buyers the true nature of what they're buying.

It is, however, not a means to help a purchaser make an informed purchase, rather it's a way for Steam and other such stores to, in the current legal and regulatory environment, legally get away with doing the very opposite and obfuscate the true nature of what the purchaser is purchasing.

Think about it this way: if the intention of Steam was to be honest and make sure purchasers were making informed purchases, then why not inform purchasers upfront in the product page in a simple way that what they would be buying was a REVOCABLE LICENSE rather than ownership of a PRODUCT, and even explain the difference, rather than hide it in a long document that requires Law training to fully understand?