I/O Stored In Water - really that bad?

It seems to be common knowledge that an outboard on a water-kept boat would be best, then an inboard, followed by a stern drive or I/O. That said, I've had my stern drive boat in the water (Santa Cruz Harbor) since April and it seems to have held up alright so far? I do use the boat 1-2 times per week which I'm sure helps, and I have a brush that I will use to clean off the outdrive if it seems overly growth-covered.

I love our $7,000 relic, but with how much we're using it we definitely need to do some upgrades and/or look to our next boat in the next year or two. With what we're looking for it seems that we'd be paying a $10,000 premium at least for a boat with an outboard. In my mind I'd ruled out anything other than an outboard but I'm starting to second-guess that assumption. We keep the boat in the water April-December and January-March it will be out of the water for maintenance and to keep it out of the rain.

So, is "you can't store a sterndrive boat in the water" just lazy internet group-think or am I really just sitting on a time-bomb?