I keep thinking about this, and the only conclusion I can come to is that businesses would still need to be able to advertise their own products in places that they own.
For example, what if I want to buy a guitar?
I'm shopping online. First, I need to pick a company to purchase my guitar from. How do I choose? Any sort of aggregated comparison of places to purchase from can be considered advertising, so they are all banned (otherwise, astroturfing would be only form of advertising). Do search engines also count as advertising? Okay, so I've found a site. How do I know I'm getting a good deal? (although this is a whole different argument about us worried about getting a good deal because maybe we over-consume, it's still a consideration).
Now, on that site, is this company allowed to advertise different brands that they carry to me? By definition of advertising, no - the whole purpose of showing me products is to make me purchase, which is the definition. So then do we reach a true communist state where there is only one option to purchase? If so, can I still not see it because it's considered advertising? Okay, fine, I need to be able to see at least one guitar, we can concede that point.
Or maybe instead I go to the store to purchase a guitar. Firstly, how do I find the store? If they are not allowed to advertise, must I organically drive past their store? Are there rules on business signs that disallow specifying the type of store, because that could be construed as advertising products? Or is that limited to a certain brand - the goal is to allow all competition equally, so it just says "guitar store"? We've already agreed (probably) that this store can't 'advertise' itself elsewhere, so the only way I will know about it is through (illegal) word-of-mouth, which is still technically advertising. Or maybe it's only illegal for businesses to advertise? Or for people who are earning money from the act? How is that defined?
Okay, anyway, I've made it to the store. When I walk in, I'm met with the same dilemma in example one - the store isn't allowed to hang up products, because that incentivizes me to purchase. Maybe I need to just say "hey, show me a guitar so I can try it" and they must present me with a randomly selected guitar to avoid bias. We continue this until I find one that resonates with me. They can tell me the price of each, but not a sale price, as that falls under unfair advertising law to incentivize me to purchase a specific brand, so brands aren't allowed to run sales anymore. I have no idea if I'm getting what I want - sure, it sounds great and feels great and I enjoy it, but maybe I could have gotten that from a less expensive guitar, or maybe I didn't realize that I wanted a different size guitar.
By this point, economies of scale have collapsed because every purchase must be organic and therefore every national retailer has been dissolved - and most likely the largest manufacturers have discovered the best way to exploit this situation, so the largest now have natural monopolies and the rest have died off because they couldn't compete and were selling direct to consumer, not stocked in stores. Speaking of which, how do stores even work? How do grocery stores work? Every grocery store is built from the ground up on advertising. The same logic applies here. Two choices on a shelf must be in identical nondescript boxes with absolutely no calls to action or differentiators listed. Therefore, the smaller companies go out of business, or maybe the companies with the largest or smallest packages. In fact, just the size of an item can be used to intuit value, so now prices must be fixed to size, and sales & coupons are outlawed.
---
All this to say, marketing in some form has existed since time immemorial. Finding value in choices is human nature.
The only way something like this could happen ("Advertising is illegal") would be a monumental wide-scale, best-effort, not-perfect set of judgement calls, which would require drastic overreach by a governing body - which would be exploited by finding weak links in the system and exchanging something they value to look the other way for a certain seller - which is exactly what got us to where we are.
One of the main reasons that we always arrive right back where we started is because the people with (less empathy, win-at-all-costs, better-than-thou, etc.) mentalities are willing and able to exploit the other group, the group that wants (peace, fairness, equity, teamwork), because the second set of values means enabling those around you, and the first set of values means taking advantage of that.
The only way I ever see healthy systems working is in relatively small groups of people where there can be shared accountability and swift action taken towards selfish behaviors, as defined as a community. Unless there is near-total buy-in, a system cannot thrive with the assurance of fairness, teamwork, equity.