Dynamic memory management is a performance enhancement. It lets you more efficiently utilize memory vs static allocation at the cost of, well, lots of types of bugs.
You can always preallocate MAX_NUM_ELEMENTS * SIZE_OF_OBJECT for all your arrays. If someone tries to send you more objects then you have buffer space for you just reject the request.
Latency sensitive programs already do this, since memory allocation is rarely deterministic (although it can be in .NET and other similar languages). Likewise a bunch of destructors going off when an object is freed in C++ also takes a, practically, non-deterministic amount of time. (Really well profiles and controlled programs can make this deterministic if allocation patterns are always identical, but that is rarely the case.)
Of course having fixed sized buffers means you have to have protocols that are aware of size limitations. Most protocols now days assume infinite memory. Everything just fails, badly, when memory does run out.
After having worked in embedded for awhile I grew to deeply appreciate planning around memory limits. Really everyone should be doing it but almost nobody is.