Sleepovers, Parties, and Play Dates...

As Summer approaches, Haley has began to insist on more play dates and sleepovers. Haley absolutely believes in play dates, parties, and sleepovers; if she had things her way, every single birthday party I throw for her would end in a sleepover! However, what's a good age to drop kids off at a birthday party and not stay with them? As a veteran mom of 20 plus years, I have attended my share of birthday parties as you can imagine, and I have seen a great deal at many of these parties. For example, moms dropping their kids off and not staying with them. Are birthday parties becoming the new opportunity for babysitting? If the invite does not say, "I'm babysitting for the day, drop your kid off", should parents assume that its okay to just drop their kid off and leave?
Personally, I think it's rude to assume that the mom, who is hosting the party, does not mind watching your kid. She already has her hands full with the party ensuring the schedule is maintained, kids are having fun, and being a hostess.
Imagine those parents with the kids who are not "good listeners" and have a tendency of having tantrums when they don't get their way; oddly, those are the first ones to drop and run!
This same parent is the very one who will have an "issue" with anyone who may have to reprimand the child in their absence, yet they are quick to "drop and run". I don't believe a child should be left unattended at a party. The reality is, knowing where your children are and what they are doing is crucial. It's great meeting new people and allowing our children to have play dates with one another, but dropping them off and leaving is tacky  rude; the mom may need assistance with the party (games, serving food and cake, crowd control, etc). There are a number of "what ifs" which may occur at a party. If you're off having a break, you're not there to deal with those issues.
When you are invited to a party and you RSVP, that means you will be in attendance. Don't assume that your gift entitles you to babysitting services for the day. Arrange play dates and get to know the other parents so that you feel comfortable mingling with them. Stick around the party and help the mom throwing it. I haven't been to one birthday party for a kid where the mom didn't need any help; there is always something to be done.
Sleepovers are something I don't do often. Before a child sleeps at my house, I have to really know their parents. It is very important to me that the parent of the other child knows me and my family and vice versa. Let's be honest, there are some strange individuals out there. Over the years,  sleepovers usually occur with cousins and best friends.
The biggest thing for me is safety. I'm a mom who does not look to others to care for my children unless they are being paid to do so. Of course they stay with family, but on average, I do not assume that someone else wants, nor needs to be responsible for my kid when I am able to do so myself.
I'd love to know what other moms think about this...