Are adults who approve of harsh punishments often victims of 'Stockholm Syndrome'?

I know Stockholm Syndrome is used with hostages and their captors but I think that the tactics used are very similar to children/young adults who experience a high degree of emotional and physical distress from authority figures.

This is probably going to be a controversial discussion but hopefully we can keep our heads calm.

When it comes to adults who experienced corporal punishment and/or ‘tough love’ tactics it seems that a sizeable majority (don’t really have any ideas about the numbers), express very strong opinions of approval; ‘I hated it as a child but I love my parents/teachers/authority figures now for it’, ‘It isn’t abuse, its just discipline. Every kid needs it.’

Now I don’t doubt that some physical forms of child rearing may be effective in circumstances, however where is the line drawn? People who experience sexual abuse and domestic violence (mainly adult women) from trusted individuals report justifying their actions with feelings of guilt and sympathy for their victims. 'If I behaved better he/she wouldn’t have to resort to molesting me ‘Everyone goes through problems. I just need to get over it, it’s not that bad.’

Even going back to my days in secondary school, I remember a few teachers in my school who were quite aggressive and strict (in the noughties not the old day of the 50s) that two students killed themselves and left a note saying that they couldn’t deal with the pressure. A lot of students were shocked but after graduation quite a number just brushed it off as mental problems as opposed to the kids being in stressful environments. According to one kid, ‘Sometimes teachers just need to do what they need to, even if it causes some people to kill themselves.’

Of course some think its ridiculous to make comparisons between sexual abuse and beating a child but is it really? I’ve found when discussing with some people who have experience with that their is some reluctance to admit that it may have been a bad thing (especially with the latter.) Do you think there’s a reasonable comparison to be made?

Nah: a lot of them are just miserable old brutes.

Without a doubt, some spanking advocates have been Stockholmed, as the OP postulates.

That being said, some spanking opponents (not the OP, but others) frequently use a roundabout moving-the-goalposts fallacy:
“Spanking is bad. Just look at all the people who were spanked, and now oppose it today.”
“But I was spanked as a kid, and I think I was better because of it.”
“That just means you’re brainwashed, and PROVES my point that spanking is bad!”*

Is Stockholm syndrome a bad thing in a family? This morning I put clothes on a toddler and drove him to school. Do we now have a shared bond developed due to my abuse.

I think there are a number of different things that are going on here.

Stockholm syndrome as I understand it results from a coping mechanism for conditions under which it is necessary for the abused to rely soley on the abuser for basic needs and security, even if in this case security only means a temporary halting of the beatings. In this case the abused will try to ingratiate themselves to the abuser in order to better meet their needs, and then internalize that ingratiation into positive feelings towards the abuser. This can definitely happen in cases of domestic violence and child abuse, and may explain why many victims have difficulty leaving their abusers, but it generally comes from a feeling of helplessness and low self esteem. Your example of 'If I behaved better he/she wouldn’t have to resort to molesting me ‘Everyone goes through problems. I just need to get over it, it’s not that bad.’ could certainly come from such a mind set but I think you other examples arise from a different set of psychological circumstances.
Your example of “my parents/teacher beat me and I’m better for it” sounds more like its coming from the direction of Effort justification. Having suffered the abuse and given the choice between thinking that the suffering served no purpose, versus the possibility that it in some way benefited them, many people will choose the latter.

In terms of abusers going on to abuse others, I think there are two things going on. The first is that for those who were raised abusively, abusive parenting techniques may be the only ones they know. So that people who were slapped for crying as a kid, may assume that the proper thing to do when a kid cries is to slap them. Secondly, abusing others is a way to take back some of the power that you lost when you were abused. So if you were beaten or molested as a child you may feel justified to beat or molest someone else because now its your turn to be on the giving side rather than the receiving side.