The two types of backtesters have slightly different purposes.
The vectorised backtest is a rather crude way to quickly test a strategy. You do it by multiplying the signal vector with the returns vector and the result is the equity curve.
The event-driven backtester is a more well thought out simulation. By making use of an event driven backtester we can stop look ahead bias to a large extent by only feeding in the data as it becomes available. This also very closely matches how your trading will take place in real life via an execution system.
We also have the advantage of building in transaction costs, liquidity constraints, and market impact. This is not something you can do with the vectorized method. (You could add transaction costs after the fact).
The event driven system you refer to from quantstart has the added advantage that you can swap out your backtester for a live model rather easily by just changing a parameter. It already creates a blotter, accounting system, pre and post performance metrics. Event driven is the way to go if you want to build out an institutional grade infrastructure.
Vectorised backtesters are for quick research ideas but if you have an event driven one, then you can forget about vectorised...
Oh and I know of funds that have implemented the event-driven architecture and I have used it personally. It's the way to go.