I'd say silicones (or lack of) do make a big difference to bounciness. I had terrible hair, fine and damaged. Tried being nicer to it (no heat, no rough towel drying, no brush only a wide tooth comb ever), it went better, went to a SLS (sodium laurel sulphate)-free shampoo (but continued to use silicone stylers, leave-in conditioners and serums etc
) and after a while it started to look really bad. Very flat, lank, dirty looking and flyaway. I then switched back to normal SLS shampoo and it went better again so I concluded my hair just didn't like these trendy SLS free shampoos. Then it went really bad again and I felt a bit stuck over what to do next. Back to the drawing board. It didn't seem to like SLS or SLS free wash and conditioner!
But basically if you use silicone stylers such as mousse, leave-ins, oils etc then you need an SLS or clarifying shampoo to get the build up out. But the SLS shampoos are harsher, more drying long term and often also contain silicones. Some hair is OK with silicones, but if your hair isn't looking so great especially fine hair which shows up more damage or lankness, then it's worth experimenting.
Best (I think) is SLS, silicone etc free shampoo and conditioner, and styling products (also alcohol free as they dry your hair out) used together. I found a website that checks the ingredient list if you cut and paste an ingredients list from your product in, it will check if the silicones and alcohol content in your hair products is good or bad (not all alcohol is terrible and some silicones are water soluble meaning they will wash out and not build up).
There are silicone free shampoos, conditioners, mousses, leave-ins etc but you need to check each product individually as sometimes a shampoo will not have SLS, silicones or sulphates etc in but the matching conditioner will have. Or vice versa. You end up tailoring products individually rather than assuming a whole range will all be OK just because the shampoo is SLS free, for example.
It's recommended that if you're switching to SLS, silicone and alcohol free products (and it needs to be all of them together including leave in conditioners and styling products) then to wash once with a clarifying shampoo before you start to get rid of any build up before you embark on an SLS and silicone free regime.