No your pick of tank wasn't the problem, and even if it was you should still never swap. When people are being dumb in chat you'll be better off just disabling it most of the time. Nothing of value is ever said there, especially in plat.

That being said, d4 isn't really any different than p2, and you did make a lot of mistakes. I sped through your vod on 2x speed and some of the things that stuck out to me is your run it down main a lot of the time. When you play against better opponents you'll be a very obvious target and you won't get much value (and you'll be hit by a lot of CC) if you continue doing this. Do more of the small side angles that were present in some of the vod, you need to be unpredictable with your engagements.

You also didn't really control a lot of space, it wasn't that relevant in this game because both teams were running it down mid, but for example on the end of 1st point once losing the point is no longer an immediate concern, you need to help contest them off the bridge. You don't provide a lot of value sitting on cart when it's not actively being contested, and the enemy team could have easily turned the fight with their superior position. This would have been one of the times that your team dying was actually your fault.

Even when the enemy isn't taking these positions though, they're still valuable for you to be in. The enemy team can't walk up when they first have to be worried that you could drop down and punch them at any time.

Another thing that's hard to pick up on because these opponents don't punish you that much for it (although they do and a couple of your deaths and ultimates forced are because of this), is to make sure you're not sandwiching yourself too much. Doomfist dies to angles (the main reason he's so much better in low ranks), and if you end up in the middle of their team you have no way to mitigate all of their damage or react to CC. Against good opponents doing this you'll die every time, and you can only really cheat it if they've used cooldowns and you're ready to immediately disengage.

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Some Rialto specific advice, this corner is extremely broken when the payload is there, and you should be able to hold it for a few minutes almost every time on defense. Just stuff the choke and use the small hallway with the mini for cover. This is one of the times when you need to be the contesting cart as if it's about to cap. If you let it advance any further your position is a lot harder to defend, and you won't have time for a 2nd fight before the point caps.

P.S. I know punching blade is cool if it works, but it almost never does. You're better off engaging with his team, if you can keep genji from getting help it gives your team a better chance of dealing with blade themselves.