True indeed (for Excel 97-SR2):

Q:\>perl -le "print $_ for 1..16383" >list.xls

Q:\>start list.xls

Q:\>perl -le "print $_ for 1..32768" >list.xls

Q:\>start list.xls

Q:\>perl -le "print $_ for 1..70000" >list.xls

Q:\>start list.xls
# "Excel did not load the whole file"
[download]

So the problem seems to lie elsewhere, like maybe not enough memory or other problems