Summoning is not drawing.

Sorry, but they're not the same word, and drawing is not a superset of summoning. So there's no reason for a rule that modifies drawing a weapon to have any effect on summoning a weapon.

Str primary classes become less limited against flyers

Currently warriors using two-handed weapons do much more damage¹ in melee than dexterous ones, especially after level 4. In return, they do significantly less damage at range, as they are limited one javelin² attack per turn, and their defining feat is not usable.

After this houserule their melee capabilities will not change, but they will be less far³ behind Dex builds at range.

This will not break anything

Unlike in 4e, magic thrown weapons do not automatically return, so a thrower build is still not really viable. Javelins keep being a backup weapon, just less bad.

Existing returning weapons

There are some returning weapons that make a thrower build viable, but the cheapest is a very rare.
And if it is returning, you do not care about free draw anyway.

So this rule does not help much, unless you play in a very low magic setting.
Otherwise you either have a returning weapon, where free draw does not matter, or you cannot affort throwing away your magic weapons. Only if no one has magic items, does a thrower build become viable by this rule.

1) With Great Weapon Master
2) They could use a bow, but if well optimized, Dex is way behind Str
3) Javelins have a bit smaller damage, and lot smaller range than Longbows