And over time even a single, small benefit can be enough to guarantee a specific rational actor will win out over its competitors.
Certainly not in all cases, but if the issue you have is that individual decisions aren't enough to pick a winner, no matter how large/important, then change the last paragraph to
>>> And of course, every decision made for how to implement the kinds of issues outlined in the above paragraph is an opportunity to pick whom to give an advantage over their competitors, too.
And this doesn't even begin to consider the issue that since the mechanism for making and enforcing the rules exists within the system of rules it creates, both fostering competition and enforcing a free market give opportunities for competitors to buy rules and/or enforcement of rules that benefit them at the expense of competitors, either directly or indirectly.
I can say in a given industry they can't pull some bait and switch... a company that relies on that tacit could go out of business, is that picking winners or regulating poor behavior?
Like anything working to maintain some level of competitiveness would be like hitting a moving target, you'll have to change what you do, address barrier of entry issues one day, who knows what next.
And yes, regulating poor behavior is absolutely picking winners/picking losers/picking specific companies to disadvantage/advantage, and not just because of issues with uneven enforcement. Determining which behaviors are disallowed and which behaviors will be policed by "natural market forces", especially when talking about modifying rules for a preexisting market, means picking winners/losers/who gets advantaged/disadvantaged. This is why encouraging/fostering competition is antithetical to making/maintaining a free market.
In order to create any free market and foster competition, an entity has to decide and then enforce the rules for the market, which allows that entity to pick a winner by the rules it choose to write and then enforce.
Plus, in mature markets, fostering competition is antithetical to maintaining the "freeness" of the market, because it requires punishing the "winners" in order to ensure competitors, by things like breaking up competitors that are able to leverage winning in one area to compete and then win in another area (ie antitrust/antimonopoly), invalidating patents/trade secrets/intellectual property/etc. when ever something is so dominant that without access to it no one can compete, and limiting how competitors can compete (eg preventing them from limiting how purchasers can use their products).
And of course, every decision made for how to implement the kinds of issues outlined in the above paragraph is an opportunity to pick who wins, too.