Because of hardware, and the fact that fixed point doesn't solve the core problems with floating point as it stands today. Its hard enough to get good stable/fast floating point hardware, much less adding the complexities of variable sized words, with variable sized mantissa/exponents.
Really, what your probably asking for is decimal floating point. Which, has its own set of limitations when implemented in hardware.
And if you happen to have an application where what you really need is more precision there are a number of bignum libraries like GMP (https://gmplib.org/) which provide that. But, throwing more precision at a problem doesn't alleviate the need to do error estimation.
Comments
Because of hardware, and the fact that fixed point doesn't solve the core problems with floating point as it stands today. Its hard enough to get good stable/fast floating point hardware, much less adding the complexities of variable sized words, with variable sized mantissa/exponents.
Really, what your probably asking for is decimal floating point. Which, has its own set of limitations when implemented in hardware.
And if you happen to have an application where what you really need is more precision there are a number of bignum libraries like GMP (https://gmplib.org/) which provide that. But, throwing more precision at a problem doesn't alleviate the need to do error estimation.