Nothing wrong with that... and I suppose it can. I generally hold that having two written references in addition to what's available on the internet is a best practice if only to cross check data. I personally have Lee and Hornady on hand. Yes, that's a bit more geared toward experimentation and once you figure out that X grains of Y powder pushing Z bullet (and you just rinse and repeat that), no you don't need a manual.
That said...
1) maybe it's that I started in experimenting with rifle loads, but I just prefer to have one around - never found a reason NOT to have one and
2) in this day and age, you may find that your favorite powder can't be found, but an alternative will work. I tend to crack the manual before I consult the internet, and I tend to cross check multiple sources if I'm entering new territory. I tend to stick to specific loads and vary very little, but I got there after doing a fair bit (not exhaustive, but comprehensive) due diligence.
(If you're just fixed on two calibers, Loadbooks may be a more appropriate/effective option - www.loadbooks.com)
I won't tell you you're fucked up if you go without, but I would encourage the investment. Just one asshole's opinion; I'll get off the soapbox now.