I just think its not sustainable long term, not just for the sake of algae problems but for the sake of the fish. One will not have fish dying of old age, but dying prematurely. Its hard to know what's died in a livebearer tank because they keep mulitplying but keep an eye on the lifespan of the longer lived fish and you'd know if what you're doing is sustainable. It may as well be, but speaking from experience, overstocking leads to inevitable problems, Algae will spread its paws early or later. And when it does, there's no return until you offload the stock, that's if the fish don't die prematurely. With good maintenance one might prolong the inevitable...
I kept a bunch of male guppies once in a "well stocked" tank. They probably lived 1.5-2.5 years max. I had only one female guppy at the time so I decided to put her in a separate tank as I had no intention of breeding the guppies. She ended up in a very lightly stocked tank. She was over 4 years of age when she died. I don't think the difference in life span was a coincidence. Then again I keep tanks for the fish, not the plants. Plants are just a vehicle to keep the tank healthier for the fish.
My advise is, get the biggest tank you can afford and fit in your house. Do not overstock it, don't even go near that. This way you can enjoy the hobby long term and have room to stock with the fish you want without overstocking... Time goes, we all have our own problems, we may temporarily lose interest, neglect the tanks for a few weeks, etc..A well stocked tank needs strict maintenance regime....each week, large water changes the minimum, etc... If you can't do that, go light 🙂 or you'll end up tearing your hairs of and even give up the hobby....