Ahh, yes I understand, it can be difficult to get your head around this.....
When we talk of "they" (as in 'they did this', or 'they did that'), it is not a particular professional sitting behind his or her screen, wrong footing the retailers, and generally causing havoc.
It is actually the whole of the market we are talking about, we are just "thinking" of the whole combined market as a single operator. That includes all of the sellers and all of the buyers combined......all of the retailers, and all of the professionals.
Wyckoff called this type of thinking the 'composite operator'.
And that is why those levels are respected, as it is not actually a single player doing all the serious trading, but the whole market combined, and when things happen it is because the overall market 'did this', or 'did that' on a particular day.
Quite a lot of stocks, in particular small and micro caps, will have little or no 'constant' professional interest, and it is mostly the retailers battling amongst themselves (both large and small), most of the time. And some of these stocks can be difficult to read at times, as liquidity can be low, supply is sporadic, & can arrive unexpectedly. This is because retailers can do unexpected things at times and at unexpected price levels (which can make the levels on the chart a bit messy in these smaller stocks). In these cases the professionals may just drop in to sell if price rallies too high, or buy if price moves down too low, depending on what their particular strategy is at the time....and what fundamentals or expected news events are driving price at the time.
That said, when a 'proper' accumulated position has been built, and a particular stock is being supported.
And price is being strongly defended against supply.... to deliberately 'mark up' the price, it can be quite obvious when you are looking at the chart, and the support can be almost relentless at times (and the opposite is true when a stock is being marked down).
When this is compared to some of the smaller stocks, it is mostly just retailers playing amongst themselves, for most of the time, and price is just generally going sideways, apart from when news announcements are released, or a serious buying or selling event takes place, and some professional interest is sparked for a period.
And about your accumulators question.
Remember that if there is to be a serious engineered shakeout (for instance), and price is going to be rammed down deliberately (to catch stops in an effort to remove future supply, or accumulate more stock.....or whatever).
This action will cost some money to engineer, and there has to be a good reason, or the promise of a decent payback to do this.
Same as when price is deliberately being marked up...it will probably cost some serious money to do, so no point doing it, if you will just be satisfying another seller, and end up with no gain overall. There has to be a good probability of success, and a decent reason or bayback in it for them.
So yes, the professionals can do things for sure, but only for a period, certainly not forever, so it has to be cost effective.
And this is done by using the media and initial price actions, to encourage the retailers to help do at least some of the work for them.......
eg- put out some good news (so the market is aware of some potential, and is conditioned for a possible move), then mark up the price a bit, and get the overall market and momentum traders excited, which hopefully will have them move the price up for you, with just a bit of added support as it is required.....or conversely, release bad media, push price down a bit using your own stock or shorts, trigger some stops and attempt to get a domino effect going, and just push it in the direction you need when it is required.
And Tom also used to say that professional disinterest could be just as important as when they are directly involved, making shareholder wait for very long periods at times is a legitimate tactic, especially when there is no news expected, or no fundamental reason for the price to move at the time.......no matter what the retailers think or expect at the same time.