I owned mx-p
I didn't notice any particular smell when new.
I mean all rubbers when new have some smell....
I generally use t05, with butterfly free chack ii, and it has shrunken a lot.
You must have a faulty nose. I would send it back. Different rubbers smell different, and some have very clear booster smells.
That aside, I sort-of agree with some of what you say, but not your conclusion. I think some people have an odd idea of what "factory boosted" means, and conflate manufacturing processes (ESN, Butterfly) with after-production boosting (Haifu, probably DHS), putting it all in the same pot, which is OK as long as you're clear about the distinction IMO.
But anyway - for me, factory boosting isn't just taking a vanilla product we can all buy and doing something special to it, it's treating the rubber with a physical or chemical process which is designed to add "tension" by expanding it. Could be adding something to a finished product, or using something during manufacturing, whatever. This will always be a short/medium term effect depending on what was used. The give-away is that the rubber shrinks after a time, most noticeable when you've had it on a blade for several months and remove it. Initial signs could also be the smell, and any signs of the rubber curling or doming out of the packet, but these aren't reliable and their absence doesn't mean that the rubber hasn't been expanded. Many boosters are odourless.
ESN had a phase where their rubbers didn't have a particular smell (just a vague chemical whiff), but had a lot of doming out of the packet, very noticeable on their softer-sponged products (aurus sound, rakza 7 soft, etc). Annoying to glue down. Then they had a phase where the rubber came flat out of the packet, but there was a very strong and obvious booster smell (TRF booster), and the rubber's performance drops over time (Bluefire M, Evolution -P, Joola MAXX, Gewo Nanoflex - I'm really surprised that you can't smell this on MX-P, it's blindingly obvious). Since then, many more recent ESN don't have the TRF smell (MX-S, Rakza X, Omega V, lots and lots of others), but that doesn't mean they aren't using an odorless booster. Who knows? I've also noticed that they don't shrink as much as they used to over time - I've got a few sheets of Omega V Asia which are one year old now, off their blades, and they still fit perfectly.
About Butterfly - Tenergy has a smell when fresh out of the packet, but it's more like a faint smell of pine, and running your finger over the sponge has a slightly oily feel (in comparison with other rubbers). The big red flag is how much tenergy shrinks over time. IMO, it's definitely factory boosted (meaning the sponge is expanded as part of the process, and the effect is going to dissipate over time, not that some random bloke takes tenergy sheets off the production line and brushes the sponge with haifu oil or some nonsense like that). This isn't me having a go at Butterfly, and Tenergy is a great rubber, but the real world is what it is - modern rubbers are made like this, and the actions of the ITTF mean that you can't legally extend the life of your rubber by boosting personally. I also think that Butterfly have changed what they do with Tenergy over the years - I got my very first sheets on release day and they didn't have the pine smell, didn't shrink anywhere nearly as much, and kept their playing properties for longer (but were possibly slower - this is a few years ago now, so I can't expect perfect recall here). It's very hard to know anything for sure - even pros aren't allowed to see everything when they visit the factory (check Freitas' comments on this in his TTD podcast), but this is just my opinion based on what I see and feel.
For another interesting viewpoint, see this blog entry, linked from tak9.com today:
http://blog.naver.com/defunct/220830269324
It's a little blog entry (I presume from Nexy themselves) about Nexy Karis M, and their "insider" view on the recent history of rubber production. Not unbiased, but interesting nonetheless.
And this is without getting into the murky world of chinese-made rubber, after-production boosting of stuff by DHS for the CNT, or touching on recent made-in-japan stiga rubbers which have a pronounced curl reminiscent of early-gen ESN. And there are still rubbers on the market which don't shrink, and so I would imagine aren't factory boosted.