When you smell blood, you gotta go for the kill.
Assuming of course they weren't dead already.

Holding back is a marketing tactic. They made the announcement for tlou2 because it would help sell more consoles to people who are preparing a large purchase early in preparation for games later.

The only reason to hold back would be if they think that showing a game later on would be better for sales.
Given that MS has pretty much given up on the games, there's not a huge reason to hold back, since console purchasers won't really have a decision to make later on.

As of now, I love Sony and their projects. To be honest, having a VR headset was a childhood dream come true to me, and, the little I played with it, around 30 hours, I loved every second.
So, I always expect them to wow me with boldness and unnexpected stuff, and I hope they do it once again.
Part of me would love to see a PSP2 with tv docking functionality and the same power that the Switch has.

Wow, what kind of sick troll-bait is this?

Will Sony hold back on showing things at E3 because they have no competition from Microsoft? It's my understanding that some people come onto VGChartz for the sole purpose of getting into arguments with others.

See OP: Exhibit A

No reason for Sony to hold back. Dreams, GoW, Detroit, GT Sport, Spiderman, Knack 2, Days Gone, will be shown. Probably going to get a glimpse of SP's project, the third party deals (Destiny 2, RDR2) & possibly third party Japanese exclusives (rumored MH, Ni No Kuni 2, BloodBorne 2). I doubt the latter though.

Plenty of times.  2014 they had LBP3 and Bloodborne out of nowhere and they both came within 12 months

Some people think Sony changed their price and presentation in 2013 just to counter MS. As if a massive corporation with shareholders that cling to every decision can just do things on a whim within a couple hours.

I'm not trying to bait anyone - I was truly hoping MS would show things that made me want to get a Scorpio (check my post history if you want), or at least spend more money in their ecosystem (I already own an Xbox One). But they showed 1 exclusive, nothing on VR, no major announcements other than the new system and Forza, as well as games available on other systems. 

I still hope (and think) Nintendo will show some great stuff, but Sony always seems to be competing directly with Microsoft. Given their huge lead already in exclusives, it seems possible to me that after the lackluster reveals of any new content from Microsoft that they might hold back announcing games that were further down the line in order to "spread the wealth" out a bit.

All companies do timed exclusive/launch exclusive stuff too. Not just MS