I'm a fan of locked lsd accel values, gives the best push out of slow corners but it doesn't work everywhere.
If the car has too much power or the tyres can't handle it then you basically end up with a drift car that is no use to anyone.
If the tyres can handle it then you will get throttle induced understeer on exit so its not great for flowing circuits where you need to stay on the throttle through the majority of corners.
On certain cars (lower powered lightweights) its a great option though, really helps to get the power down and keep the drive wheels constant.
A broad sweeping statement is rarely accurate, some cars work with a tight diff, some really don't. Start your own garage, post your own tunes, don't go judging other peoples work unless you are sure you can do better.