In comments you indicated that you had a very old latex release. In LaTeX releases prior to 2015, there were by default only 256 registers of each type available. A float insert needs a register for a box (latex savebox), dimen, skip (latex length) and count. So if you allocate more registers for floats there are correspondingly fewer of these registers for other things and packages that use a lot (pstricks for example) may fail. However there is no harm in trying as if it avoids the error there are no ill effects.
In any current release there are over 32 thousand registers of each type available and so this is less of an issue. More floats are allocated by default and there is an \extrafloats
command so that you can do \extrafloats{100}
to give yourself 100 more if needed, no package is required, although the morefloats
package is still available for compatibility reasons and uses \extrafloats
internally if it is available.